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Sister Agatha: The World's Oldest Serial Killer

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Sister Agatha is 118 years of age, whose vim and vigour would put the most robust athletes to shame. However, during a routine check-up, her doctor claims that she has just a week to live—inconvenient, seeing as the beloved sister once made an improbable vow: to be the oldest person in the world. At last count, she was the fifth.

Never one to admit defeat, Sister Agatha concocts a bold Plan B. Using her final days, she intends on travelling the world to meet the only four people whose birthday cakes boast more candles than hers.

And then, one by one, she will kill them.

208 pages, Kindle Edition

First published August 3, 2016

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About the author

Domhnall O'Donoghue

4 books39 followers

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5 stars
205 (43%)
4 stars
134 (28%)
3 stars
88 (18%)
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24 (5%)
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16 (3%)
Displaying 1 - 30 of 70 reviews
Profile Image for Mark.
1,688 reviews
May 23, 2022
I know a lot of us readers take the blurb exclamations of ‘Hilarious’ and ‘One Of The Funniest Book I Have Read’ with a pinch of salt, but for me it was true with this book, it is a real hoot from page 1 right to the end, I dont think I was without a grin throughout, the humour is spot on, sometimes via just a really funny situation Agatha has got herself in or other times the gentle wry observations of people and places, it cannot fail to make you smile and we all need a bit of that 😊
Agatha is a scream, the worlds 5th oldest person and she intends to be the oldest and sets off on a world journey to meet her competition..to say more would ruin it but she ends up in some real old pickles
The author brilliantly takes you on her quest and you cant help but love her, shes a real character, some of the other characters we meet are equally as memorable, my mind was in overdrive picturing them
A really, really funny book, and look forward to reading the authors next book which as soon as I had finished this I went and bought

10/10
5 Stars
Profile Image for John.
291 reviews
December 27, 2020
Having read another book by this author - Colin and the Concubine - I went out looking for more of this author. This is the next book I found.
The blurb and other reviewers tell the story theme. The book is full of humour - Irish/British - and rubs shoulder with dark comedy at times, considering story revolves around the actions of a nun intent on gaining a personal achievement by any means available - even murder.
The story runs at a nice pace and is well editted.
Recommended read.
Profile Image for Irene Sauman.
Author 13 books38 followers
February 17, 2018
This was a fun read with typical Irish charm, and (slightly) twisted tongue-in-cheek humour. After being thwarted in love at the age of nineteen, Sister Agatha joins a convent. Now at 118 years of age she is the fifth oldest person in the world, and with a supposed one week left to live - if you believe what she has heard from her doctor - she sets out to become the oldest living person in the world by eliminating the competition.
She travels to the Sahara desert, Warsaw, Chicago and Venice experiencing much as she undertakes her mission. She is aided in this by the actions of others, past and present - including her targets.
The characters are quirky but real, with the most human of foibles. The life vignettes of the assorted cast, and their effect on the outcome, are well drawn. An enjoyable light read.
Profile Image for Maria.
515 reviews91 followers
February 28, 2025
This book that supposedly was “hilarious” did not produced a single laugh, cackle, guffaw or even a small chuckle instead lots of rolling of eyes and sneer from this reader. What a letdown!

A great premise but this book did not delivered what it promised. I will explain why I think this book is not funny; the story is told from the writer’s point of view meaning Sister Agatha does not have a voice and presence in the story. Some examples, can you imagine Joyce from The Thursday Murder Club without a voice having Osman describe everything she does and that’s it? Mrs. Pollifax not interacting with anyone just the writer telling you what she is doing or even Finlay Donovan not being able to get a plan across to Vero in her own unique way?

Sister Agatha is NOT the hilarious character this author is trying to sell. You can tell she is a figment of his imagination that go from one silly and infantile situation after another. Having characters perform and say funny things is what makes you forget you are reading a book. Sister Agatha needed to be heard, she needed lines and dialogue in order for her to be a character in this story!

I am a heavy consumer of Irish capers because of their humor, this book was not humorous.
Profile Image for loopyloulaura.
1,540 reviews21 followers
August 6, 2022
Sister Agatha is 118 and the fifth oldest living person. She believes she only has a week left to live and it is her ambition to be the oldest in the world. She has a week to kill off the four people older than herself...
What a book! Sister Agatha is an absolutely fantastic novel, packed with adventure and humour . I had a smile on my face as I whizzed through the pages, enjoying every nuance of plot and character.
The depth and layers of plot are superb. Agatha was thwarted in love as a teenager and joined the convent where she has led an exemplary life. Now she has an ambition to be the oldest person in the world and is prepared to break her vows to commit murder. Agatha's plans don't work out quite the way she anticipates leading to wonderful plot twists.
The luck or coincidences were a joy to read. The style of writing is light hearted, full of funny commentary but also wise.
There are a number of peripheral characters whose lives are altered by Agatha's journey. There are little mentions in passing of the other nuns which hint at the personality behind the veil. All of the characters were brought to life so well with very human foibles. However it is Agatha herself who truly shines, immersing us in her mission.
Sister Agatha is fun and quirky and I loved the escapades of the incredible nun.
Profile Image for Tissie.
345 reviews20 followers
June 20, 2022
So, I don't really agree with the 'hilarious' take everyone seems to label SIster Agatha with. It's not because you have an unfunny book in your hands--far from it! Sister Agatha is an entertaining novel, and humorous parts are def present; it's just not a guffwaf-inducing story, since the merry tone is a bit more subdued that I thought before starting it.

If you ask me, it's a feature rather than a bug.

However, the thing that makes Sister Agatha noteworthy is O'Donoghue's attitude towards spoilers. A huge one is right there, just a few pages in: you're following Agatha, a dynamic elderly nun whose life seems to be hunky-dory, until the hunky-doriness starts cracking, and hey! Spoiler!

Thank. You. Thank you for straying from the beaten, boring path and offering me a different perspective.

I mean, I respect the majority when it comes to spoilers, I do. I just don't understand it. Being spoiled is maybe the best thrill I get out of books, being able to know what's going to happen rather than panicking together with the characters--wow. Best feeling ever and one of the main reasons I read.

Anyway.

The story itself is entertaining, all the characters have a great inner voice--yay! O'Donoghue's writing skills are excellent, and Sister Agatha showcases them in a beautiful way.

I couldn't be more pleased, highly recommended.
Profile Image for Frankie.
1,035 reviews75 followers
June 23, 2022
How much do I love this book???

Honestly, I don’t have the adequate words to say, this book is a stonking great read from start to finish, I haven’t laughed so much while reading a book – my family was certainly giving me odd looks as I sat in the corner chuckling over the exploits of a murderous nun.

I have to be honest and say whenever I see a book (or film/tv show) which has a few reviews quotes stating how fun and hilarious it is, I do wonder if it will be as funny as the reviews claim. Most of the time I never think so (maybe I have a weird sense of humour) but this hit all the right marks, it really is as laugh-out-loud funny as it claims to be.

Sister Agatha is a real blast, I love this little nun who sets out on a murderous adventure across the globe. She is a real hoot, am 118 year old, quick-witted and unassuming old lady who thinks nothing of bumping off her competitors for the crown of being the oldest person in the world. She has set herself a task and she is determined to carry it out to the letter, time to pack as time is of the essence, having just a week to live she can’t dally.

I love that this isn’t just about a doddery old lady with murder on her mind, this is a tale of living life to the limit, discovering or experiencing everything that life can bring and obviously having a jolly time as you go.

I’ve not read any of the author’s previous work before this (why for heaven’s sake not?) after this I am off to add all of Domhall’s other books to my need-to-read list. I am well and truly jumping aboard the Domhnall O’Donaghue bandwagon, I am hooked with his cheerful, incredibly fun and easy-to-read writing.

Sister Agatha is exactly what it says on the tin, I was hooked from the first line and sped through the pages with lightning speed as though I had less than a week to live. I love the quirkiness and the marvellous eclectic characters and tongue-cheek comedy, this is one of those books where you know it would make a brilliant film; hint, hint to anyone reading this (I am envisioning Maggie Smith, Julie Walters or Zoe Wannamaker).

This is seriously funny, and highly original, I loved it and cannot recommend it enough – if you read just one book this year, then make it this one, I can guarantee you won’t be disappointed!!
Profile Image for Renata.
Author 1 book14 followers
June 23, 2022
Sister Agatha ranks fifth among the oldest people in the world. On realizing she doesn’t have much time left to live, she embarks on a quest to make it to the top of the list. She has never stepped outside Ireland all her life, and now needs to travel across the world to meet her four targets. As the nun sets out to eliminate her competitors , the reader is treated to a hilarious ride through the eyes of the geriatric assassin. Does Sister Agatha achieve her goal of topping the list of oldest living person in the world, or do her age and vocation come in the way?

World’s Oldest Serial Killer is one of the funniest books I have read, and one of my best reads this year. I loved the darkly comic concept of a senior citizen serial killer. Sister Agatha is a brilliantly conceived protagonist – keeping the reader guessing whether she’ll follow in the footsteps of Saint Agatha, the patron saint of Sicily whom she was named after; or Agatha Christie, her favorite author and namesake.

All the characters have been well developed, and the novel follows a steady pace throughout, as we meet the top four oldest people in the world. The book is a laugh riot from start to finish, and is highly recommended for readers who like dark humor. It’s hard to believe this was the author’s debut novel. Domhnall O’Donoghue is a wonderful writer, who brings the Irish sense of humor to this unique story. There are some really funny one-liners and witty dialogues. Well worth the reading time.

Profile Image for Iosua Brían.
1 review
November 8, 2016
What an exciting debut novel from a clearly talented author who lives up to the Irish stereotype of having the gift of the gab.
In Sister Agatha, he has created a character that one cannot but adore with her wit, her power, her determination, her spontaneity and her warmth. How refreshing in this day and age to see such a powerful older female character blaze across the world in her endeavours to obtain the coveted title of the World's Oldest Person.
The style, tone and humour of the author make it difficult to put this book down and the suspense created brings the reader along as a witness to Sister Agatha's greatly entertaining adventure.
The use of flash backs and the vivid portrayal of the evolution of all the characters make this an absorbing, yet light hearted, read. Each character has their story to tell - from the nasty and spiteful Mrs Keogh to the hilarious gambler fanatic Sister Fidelma - and the presence of strong women, as I've I highlighted before, is a welcome addition.
I can't wait to see what the author produces next!
Highly recommended
Profile Image for Lauren.
392 reviews7 followers
June 20, 2022
Full of twists, turns, and incredibly entertaining coincidences, this book is a fun romp around the world following Sister Agatha as she perseveres in her quest to be the world's oldest person. It's short and light and a whole lot of fun, but will keep you guessing.

Sister Agatha is definitely the star of the show: full of determination and with more luck than a four-leaf clover, but perhaps a little less clever than she thinks. However, we get snippets of the people whose lives intersect with her adventures, from a Scottish momma's boy to a scheming blackmailer, with many of them reappearing in clever ways.

Deftly written, handling perspective shifts and flashbacks to keep the action moving, you almost don't realise how neatly everything ties together until the end! Suspend your disbelief and sit back to enjoy the ride.

Disclaimer: I received a copy of these stories via Rachel's Random Resources; all opinions are my own. For more reviews, check out my blog!
Profile Image for M.J..
Author 111 books257 followers
June 20, 2022
Sister Agatha is a wonderful comedy. Sister Agatha herself is a fabulous creation, as are the people she meets and interacts with.

I thoroughly enjoyed the interactions and intersections throughout the story, and Sister Agatha gets to meet a varied cast of characters, and they too have their own stories told throughout the narrative. The whole premise is really quite clever, and thoroughly enjoyable.

If you're looking for a gentle comedy, dark in places, then this is definitely for you.

Profile Image for Sherri Bryant.
1,368 reviews73 followers
August 27, 2022
Please, for the love of God, don’t follow in my steps and wait too bloody long to read this book. I say “Bollocks!” to real life and anything else that might interfere with picking up this book right now and diving in.

The former Butsy Miller, now known as Sister Agatha, has been on this Earth for a very long time and has seen her share of trials and tribulations. She’s known love and heartbreak. At the spry age of 118, she has lived through quite a bit and outlived her family and friends. She has no reason to think that this will change, but during a routine visit to her doctor for her check-up, she is given the impression through a major misunderstanding that she has about a week to live.

Obviously, this will not do, as it has long been her aspiration and goal to be the oldest person alive on the planet. The problem is that she’s the fifth oldest living person, so she decides she will abscond with the convent’s debit card and travel the globe to locate the four older persons…and kill them. Yes, you heard correctly. This sweet, very old and innocent appearing nun is out for blood. Her quest will take her to Tunisia, Chicago, Warsaw and Venice.

First, I need to extend all love, appreciation and many kudos to the very talented Domhnall O’Donoghue for giving us a story that has so many twists and turns, but keeps the reader fully engaged. The story switches between the past and present so seamlessly and sidebar snippets are inserted that, at first glance, appear irrelevant to the story, but quickly and cleanly tie in and connect to the story. A very brilliant writing technique that I have never seen done so successfully.

I had so much fun tagging along with Sister Agatha. I liked her immensely and really didn’t want to see her start murdering people, but a girl’s gotta do what a girl’s gotta do. She’s already in trouble with the man upstairs for the theft of the debit card, so she really doesn’t have anything to lose, right? Along the way, she meets many interesting and entertaining characters that added to my enjoyment of this story.

My Final Verdict: This story shocked me, surprised me and made me laugh aloud numerous times. I also got a little misty-eyed at parts. Sister Agatha felt like family and I felt quite protective of her. I highly recommend this book to everyone to read right now and many thanks to Domhnall O’Donoghue for giving Sister Agatha to me. I shall cherish her always.

Disclaimer: I received a complimentary copy of Sister Agatha: The World’s Oldest Serial Killer from the author in exchange for an honest review.
Profile Image for Deirdre Roberts.
74 reviews2 followers
July 19, 2022
This is the first book that Domhnall O’Donoghue wrote but the only one I hadn’t read until now. Given how much I enjoyed Crazy for You and Colin and the Concubine, I had to give it a go – it was worth waiting for.

At 118 years old, Sister Agatha is the 5th oldest person in the world. She is as fit as a fiddle and assumed that she would eventually be the oldest living person in the World. Due to a misunderstanding at her doctors surgery, she believes that she only has a week to live. Sister Agatha decides that her only option is to kill the only 4 people in the world that are older than her.

The plot takes a twist early on, taking the book from what could be a crime novel to a highly entertaining read. Domhnall's talent for entertaining writing matches his ability to tell a fast-paced story whilst creating a vivid picture. It was a joy to read.

A well-deserved 4 stars
Profile Image for Cathy Geha.
4,345 reviews119 followers
August 1, 2016
Sister Agatha: The World’s Oldest Serial Killer by Domhnall O’Donoghue

Asked by the author to read his book in exchange for my honest review I have to say I have done just that. I read the blurb and thought, “Now, what will this be about?” and then said, “Let’s see.”

Sister Agnes has lived many years and has never needed her passport till she sets out to accomplish her life goal of being the oldest living person on earth. Her story is told with some flashbacks as she moves forward with her quest. She travels to Tunis, The USA, Poland and Italy to meet up with the people who are older than she is. How each of those standing in her way is dealt with is…interesting. With a bit of the newspaper and travel journalist writing styles to enjoy this was a fast-paced, snappy, educational and interesting story with insightful vignettes into the lives of side characters that enlivened my time with Agatha. What a character she was and what a life she led. I believe her last decade on earth might have been the most rewarding.

If you are in the mood for something different that will take you to interesting places and allow you to meet new characters then this is a book I would recommend to you.

4.5 Stars
Profile Image for Wall-to-wall books - wendy.
1,065 reviews22 followers
June 27, 2022
MY THOUGHTS -

This was a very odd little story... oddly amusing, oddly funny, and oddly entertaining!

I love books that dare to be different or quirky and this one fit the bill! This was dark humor at its best. If you like that kind of thing then you will love this book.

This had a great cast of characters. I couldn't wait to see who and what personality would pop up next. I fell in love with Sister Agatha, even though she was at times unlikeable and... odd - I loved her!! In a way she kind of reminded me of Betty White!

Someone else said it was addictive. That's exactly what it was! Addictive! Once I started I couldn't put it down.

The author's writing style was a little different than I was used to, but once I got into the story it didn't really bother me anymore and it started flowing.

I recommend this if you are tired of the same ol' same ol' and want something different, just for fun. :-)

I voluntarily posted this review after receiving a copy of this book from Rachel's Random Resources - Thank You!!

Profile Image for Tammie Painter.
Author 54 books127 followers
October 7, 2022
If you feel the quirky-senior-who-goes-on-adventures has become a wearisome and predictable trope, you haven't met Sister Agatha.

Sister Agatha has one goal in life and that's be the oldest person in the world. At 118, she's done pretty well, but there's four other people ahead of her in the age line. What's a goal-oriented nun to do? That's right, steal the nunnery's credit card and jet around the world so she can kill off her competition.

The concept is ridiculous, but Sister Agatha is completely believable (and devious) as she sets about her task. Happenstance plays a huge part in her aims, and it was delightfully hilarious watching all the pieces fall into place. Throughout the story, you get snippets of Sister Agatha's past and learn why she became a nun and why she invented this goal for herself.

The book is short, full of laughs and charm, and is bound to entertain. I'll definitely be seeking out more from this author : )
Profile Image for Alexander Fitzgerald.
4 reviews1 follower
October 18, 2016
I'd been recommended this book by a friend so took the plunge. As it was the author's debut, I didn't know what to expect, but couldn't put it down. In fact, I'd have finished it one day if I hadn't needed to sleep - it's that un-put-down-able.

The protagonist, Sister Agatha, is a beautifully conceived character. You get a great sense of her background, her motives and her character.

The book moves at a fierce pace and introduces a host of characters, all of whom are wonderfully described; while the plot is fun and unpredictable.


In short, it's a riot of a read: super fun and full of surprises. Enormously recommended!
2 reviews
October 21, 2016
Liking the sound of this dark comedy about a serial killer nun, I was looking forward to reading it & I wasn't disappointed. Sister Agatha is not just an "Irish story set in Ireland". We are taken on her adventure as she sets about achieving her goal & all the people she meets are rounded characters with their own back story. The descriptions of the various cities she visits and the historical references make the book come to life. There are many laugh out loud pieces. I may not reach anything like 118 or be a serial killer, but I would hope to have some of Sister Agathas energy as I bimble into old age
1 review
October 28, 2017
Sister Agatha is a wonderfully funny and witty read. Sister Agatha is a feisty and funny character who's enthusiasm and determination to see out her plan of becoming the oldest person in the world really is a page turner. Sister Agahta is full of surprises and keeps the reader engaged with it's fast pace throughout. I loved the description of the various cities she visits and historical references makes the book come alive. I look forward to seeing what this fine author brings to the table next. I would highly recommend sister Agatha as a funny and most enjoyable read. Helen
Profile Image for Cyrene Olson.
1,413 reviews17 followers
August 1, 2017
Uncaged Book Reviews:

Sister Agatha is a whopping 118 years old she miss hears her doctor’s conversation. With another stating that she has only a week to live. So in her last week on earth she is determined to be the oldest surviving person not the fifth. I really liked this story as it was full of dark comedy and you really had to love Sister Agatha who is a one of a kind person. This book being the author’s first book I’m exited to see what he comes up with next. Reviewed by Jennifer
1 review
October 19, 2016
I loved it, a very entertaining read! I couldn’t put it down. I was so eager to see where the naughty but nice Sister Agatha was off to next, on her quest to become the oldest person in the world. The vivid and descriptive writing makes Sister Agatha come to life. A very well written and witty book with plenty of laugh out loud moments.
I can’t wait to see what this author produces next.
1,482 reviews25 followers
November 15, 2025
What a crazy fun read this was. A nun on a mission to ensure anyone ahead of her in the oldest person alive list which takes her around the world, what's not to like?

Sister Agatha is a terrific character. She's determined, resourceful and adept at getting herself into and out of difficult situations. I loved it.
3 reviews
Read
April 2, 2019
Love love love it
Such a great writer!!
I read it in one go !!! Who needs anti depress
Read this guys books!!!
Profile Image for Cate.
3 reviews
Read
April 2, 2019
I read his second book first and then found this when searching for MORE
This is one right good writer and I long for MORE !!!! Hilarious stuff ! What an imagination !!
Profile Image for Helen the Bassist.
379 reviews9 followers
April 28, 2024
4.5*
Completely not what I was expecting but I loved it nonetheless. If you want something heartwarming and life-affirming, read this.
28 reviews
November 17, 2024
An expansive shaggy-dog story.

I have a weakness for books with quirky humor, so obscure they acquire a near-cult status. One of my favorites is Don McGuire's 1600 Floogle Street, about an ex-burlesque comic who runs for Governor of California against a declining movie actor named Donald Duggan. In this same group I include Max Beerbohm's Zuleika Dobson and Mark Twain's 1601. O'Donoghue's Sister Agatha belongs to this same group. O'Donoghue is a masterful anecdotalist and storyteller. He is not so much of a joke man as a humorist. The fun rises from character, ironies, and plot twists rather than one-liners. This makes it hard for me to quote anything. I can tell you, however, that I zipped through this book and wound up entertained and satisfied. He's got two more novels I will check out.
1 review
December 24, 2016
Now this is a very clever and well written debut novel. The travel sections are particularly insightful and highly humorous. The writer has a keen eye to detail and the plot is both unique and engaging. Very difficult to put the book down. A wonderful holiday read. I certainly recommend this book and look forward to more hilarious offerings from this exciting novelist.
Displaying 1 - 30 of 70 reviews

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