Undertow: A Merfolk Legacy

Under #4

by M.N. Arzu

The City wants answers, and it wants them fast. A messenger is sent to the surface, ordering the Council to explain themselves and their misguided decisions, a demand that effectively means someone needs to return to the one place they swore never to go back The City itself.

Meanwhile, after a few delays and more than a few misgivings, the talks between the UN Committee and the Council are finally happening, diverting merfolk attention to what the future might bring.

Divided between The City and the UN talks, no one is prepared for Admiral Coleman's deceptive plan, one that seeks to break the weakest links amongst the Brooks family and those around them.

From the depths of the ocean to the perils of high level diplomacy, the fourth book in the series explores what it means to choose between duty, honor, and family bonds.

372 pages, Kindle Edition

Published July 8, 2025

About the author

The first series that captivated my imagination was The Chronicles of Narnia. The idea of having a secret world —imaginary or otherwise—was so appealing I had to create my own as soon as possible.

Fast forward a couple of decades, and I have gone through the dark realms of Stephen King, to the lighthearted girl power of Sailor Moon. I've fought monsters on Zelda, and become a die-hard Roswell fan. I've lost my memories with Jason Bourne, and I've lived a thousand lives alongside vampires, immortals, fairies and goddesses.

Magic and science blend into the tales I bring to life, and I am constantly striving to capture the essence of the great storytellers from my past.

Reviews

[Sunny · Rating 5 out of 5]

"Undertow" is everything I hoped it would be to wrap up this story arc! The Under Series is my all-time favorite Sci-fi series and if you have read the first 3 books, you will absolutely love book 4. If you haven't discovered this amazing series yet, by all means, grab book one NOW! I think that teens as well as adults will want to dive into this world. I'm going back to book #one now and binge on the whole series, again. The world building in book 4 is especially wonderful, and has a fantastic,"I did Not see that coming!" twist from the brilliant mind of this author. When You've finished this series and feel that it was over too fast, not to worry, she has a stand alone book called "The Librarian". I simply can't decide which of these is my favorite. Thank goodness, I can have them all! My thanks to the author for this advance review copy. I truly loved every minute of it. I am hoping for a movie or TV series.
M.N. Arzu is going to be an author you remember for years to come!

[Marilize · Rating 5 out of 5]

I have been looking forward to this book, and now it is finally here!

These characters have been living rent free in my imagination for years. And you know the author gets it right, when there is even a villain you have a soft spot for. It was also satisfying to see that some of my speculations turned out to be right.

If I could give this book 10 stars, I would. An altogether satisfying ending to a gripping series.

[Erick Dubon · Rating 5 out of 5]

I’ve been waiting for this book for so long! I had missed the characters and this amazing world build that M.N. Arzu built. I love the character dynamic and the family sense that is very strong in her stories. This is a piece of Sci Fi you definitely must read, and let yourself be transported to this world where Merpeople walk amongst us. You don’t get to see mermen stories as much, the characters by this delivery feel very much like old friends. Enjoy your read!

[Tabitha Ritchie · Rating 5 out of 5]

Loved it! I don't know if this is the end or not but it tied up loose ends. Good plot, loved the characters, a great and more realistic take on the merfolk mythology. If I could I would wipe my memory and go back and read the series again! If you liked the movie Splash, you will like this series.