Deep Roots

Siobhan O'Brien #2

by Sung J. Woo

After solving her first case, Siobhan O’Brien faces her biggest challenge yet – Thanksgiving!  With her lawyer boyfriend Craig in tow, Siobhan travels to Minneapolis to endure small talk with the extended O’Brien clan and chow down on some seriously delicious turkey and dressing.  Everything’s swell until her sister-in-law Gwen tells her about her brother Sven's frequent late-night meetings with his co-workers.  Since Siobhan’s next case is just a ferry ride from their house in Washington state, she asks for Siobhan’s help.
Big sister is happy to oblige, though she’s got her hands full.  Hired by Phillip Ahn, a Korean artificial intelligence genius with his own personal island in the Pacific Northwest, Siobhan enters the strange, sequestered world of the uber rich, where Ahn, his wife, his two ex-wives, and his five children all live under the same gilded roof.
Ahn brings Siobhan to his estate because he swears that Duke, his youngest child and only son, is an impostor.  Is Ahn crazy, or is Duke really someone else?  And could it be possible that Sven’s troubles are somehow linked to Ahn’s?  As Siobhan digs into these dangerous mysteries, she learns that family secrets have some very  Deep Roots .

Genres: Mystery

320 pages, Paperback

Published June 17, 2025

About the author

Sung J. Woo's short stories and essays have appeared in The New York Times, PEN/Guernica, and KoreAm Journal. He has written two novels, Love Love (2015) and Everything Asian (2009), which won the 2010 Asian Pacific American Librarians Association Literature Award (Youth category). In 2014, Everything Asian was chosen for Coming Together in Skokie and Niles Township. A graduate of Cornell University with an MFA from New York University, he lives in Washington, New Jersey.

Reviews

[Susan · Rating 4 out of 5]

This is really a strange combination of mystery and science fiction. Adopted from Korean as a child, Siobhan O'Brien is now a private detective in New York State. She's called to the island-estate of a Korean-American billionaire to determine whether is son and heir is really his son. She's puzzled by the assignment, but the money is good, so she'll give it her best shot. The billionaire lives with his two ex-wives as well as his current wife, his children and grandchildren, an array of well-trained servants, and drones galore, but he's disappeared by the time Siobhan arrives to work. She sends for her part-time college student intern, a computer whiz called Beaker, and together they find the monstrous crimes in the family's past. Personally, I enjoyed the characters more than the plot, but others may differ.

[Nina Miller · Rating 5 out of 5]

In this second outing for our Korean adoptee Siobhan O'Brien, we find her face-to-face with the gloriously nutty and exceptionally spoiled Ahn family. Through science, technology, and a little O'Brien signature sass, author Sung J. Woo brings a lot of fun in this mansion merry-go-round of a story.

This time, we meet Beaker, now her intern, who is an excellent addition to her sleuthing. We see her learn of the lives of the immensely privileged and view them through her lens of small-town upbringing, personal cultural clashes, and a grounded (if not a bit sheltered) life.

Woo explores identity, culture, and family dynamics in a fun with unexpected turns romp! I recommend reading both of these fabulous mysteries and getting to know the witty and wonderful (could be your BFF) detective O'Brien.

[Jonathan · Rating 4 out of 5]

A solid second book in the Siobhan O'Brien detective series. A spin on Crazy Rich Asians, there was plenty of technology on display as she tried to figure out if the heir apparent was the real heir. Maybe a bit too much computer mumbo jumbo, although at least it sounded better than most. She's a pretty wonderful character, with a wry and funny outlook on life who stumbled into the detective business. I hope we continue her adventures.

[Gretchen · Rating 4 out of 5]

Enjoying Siobhan O'Brien and her sluething as well as her witty humor.

[Nessa’s Book Reviews · Rating 4 out of 5]

Book two in the Siobhan O’Brien series takes everything I loved about Skin Deep, the offbeat humour, the bite, the dry-as-a-martini narration and deepens it (fitting, given the title).

This time, the mystery’s set against two wildly different backdrops: a chaotic Thanksgiving with Siobhan’s Irish-American family in Minneapolis (peak passive-aggressive Midwest energy) and a tech billionaire’s cult-adjacent island compound in the Pacific Northwest. Talk about whiplash, in the best way.

Siobhan’s voice is still the star. She’s wry, cynical, self-aware, and just the right amount of emotionally guarded. Watching her navigate everything from nosy aunts to AI-obsessed megalomaniacs is just pure delight.

The mystery itself is more high-concept than in book one. Think identity theft meets family drama meets sci-fi tinge, but Woo pulls it off without veering into the absurd.

Bonus: there’s some nice character development and more insight into Siobhan’s family history. If you liked Skin Deep, this one's even sharper and funnier, with emotional beats that hit harder.