Unsolved Waters, The Undertow Murders
⭐ Debut Novel · Psychological Thriller · 2026
Unsolved Waters
The Undertow Murders
By Marielle E. Suárez
Featured Pick · Between the Wines Book Club
Our Rating
🍷🍷🍷🍷🍷
5 / 5 glasses — a debut worth every sip
Genre
Thriller
Pages
323
Pace
Slow Burn
Club Vote
5/5 ⭐
Enter the water 🌊
Unsolved Waters
View on Amazon →Plot Summary
What's it about? 🌊
Detective Sofía Méndez has one unforgivable failure in her past. Five years ago, she led an investigation and found the answer nineteen days too late. She has been trying to sleep since.
Now, in a colonial cistern beneath the oldest fortress of the Americas, another body has been placed with the kind of care Sofía recognizes from her worst nightmares. Hands stained cobalt blue. Body arranged like a saint prepared for veneration.
And it is only the beginning.
As more victims surface—young Dominican men connected by nothing anyone can see, staged in locations no ordinary killer would choose—Sofía traces a design that shouldn't exist. Someone is transforming Santo Domingo into a cathedral of the dead.
But Sofía is not the only one moving toward the truth. And when the killer's design finally begins to unravel, it will not unravel where anyone expects. Meanwhile, a journalist searches for her missing brother. A wife opens a drawer she has avoided for twenty-two years. And a partner Sofía trusts absolutely may have been standing three steps behind her all along.
When the November flood arrives, the city that has kept every secret will drown along with them.
⚠️ Content warning: violence, grief, religious themes, references to abuse, and depictions of drowning.
Pairing · Dominican Flavors
What to eat while you read 🍽️
Dominican dishes that pair with the atmosphere of Unsolved Waters. Perfect for a themed book club night.
Mangú con Los Tres Golpes
The exhausted detective's breakfast
Mashed green plantains, sautéed red onions, fried cheese, salami, and eggs. Sofía would eat this at dawn after not sleeping. Comfort food for the sleepless.
Sancocho de Siete Carnes
For the middle chapters
The seven-meat stew that defines Dominican Sunday afternoons. Slow-cooked, rich, unmistakably ours. When tension is building and you need something that anchors you.
La Bandera Dominicana
The everyday plate
Rice, beans, meat, salad. Five centuries of Dominican identity on one plate. Serve it at your book club and toast to the country that made this story possible.
Chicharrón de Cerdo
For the darker chapters
Crispy pork rinds with lime and salt. Something to bite through the tension when things get heavy.
Tres Leches Cake
For the epilogue
Rich, sweet, impossible to resist. For when you need something sweet after everything the water took.
Habichuelas con Dulce
For the religious themes
Sweet cream of beans, traditional for Lent. Given the novel's religious motifs, especially fitting for the book club conversation.
Between the Wines 🍷
What to sip while you read
Because this book is best enjoyed with a glass in hand and the water rising.
A bold Malbec
Act I · The opening chapters
For the first body in the Alcázar cistern. A dark Argentine Malbec—full-bodied, notes of blackberry and leather. It matches the weight of what Sofía discovers.
🍇 Try: Catena Zapata Malbec Argentino
A deep Cabernet Sauvignon
Act II · The pattern reveals itself
As the investigation deepens, move to a Cabernet with structure and mystery. This is the wine for late-night reading, when you can't stop turning pages.
🍇 Try: A Napa Valley or Mendoza Cabernet Sauvignon
A cold Dominican beer
For the Malecón chapters · Anytime, honestly
Because sometimes a thriller doesn't need a wine list. Sometimes it needs a Presidente jumbo, well-chilled, sipped slowly while the pages turn. This is the drink Sofía would grab at the colmado after a bad day. This is the drink your book club deserves when the humidity of the story starts to feel real.
🇩🇴 Try: Presidente (the classic), Bohemia (for the purists), or Presidente Light if you're planning to finish the book tonight
Dominican rum, neat
Act III · The storm arrives
For the flood. For everything that gets carried away. There is no substitute here—only Dominican rum, sipped slowly, no ice.
🇩🇴 Try: Brugal 1888, Barceló Imperial, or Ron Bermúdez Aniversario
A glass of rosé
The epilogue · Playa Rincón
After everything, something lighter. Something that tastes like coming back to yourself. Rosé for the final pages, when the water has receded and the survivors are figuring out what they saw.
🍇 Try: A dry Provençal rosé, well-chilled
Not drinking? We got you.
🥬 Green juice (kale, apple, ginger, lemon)—the drink Sofía makes on mornings her coffee maker still smells of yesterday's mistake.
🌺 Cold hibiscus tea (jamaica)—deep cobalt-red, dramatic, unmistakably Caribbean.
💧 Sparkling water with lime—for reading late, when you want to stay sharp.
Book Trail · The Setting
The book trail 🗺️
Every location in Unsolved Waters is a real place in Santo Domingo. Marielle walked each one during the writing, often at hours when the tourists were gone. If you ever visit, here's the route.
Alcázar de Colón · Station One
The oldest colonial fortress in the Americas, built in 1510 for Diego Columbus. Beneath its foundations lies a sixteenth-century cistern that few tourists ever see. In the novel, it becomes the site of the first body.
💡 Real-life tip: Standing in the plaza at dusk, when the streetlamps flicker on, you can understand why this place became the novel's opening scene.
Acuario Nacional · Station Two
On the eastern edge of the city, the National Aquarium's massive shark tank glows an unnatural cobalt blue at night. The second victim is staged where tourists gather during the day and silence swallows the space at night.
💡 Real-life tip: Go at opening hours to feel the emptiness. The silence is part of the atmosphere.
Plaza de la Cultura · Station Three
An open-air plaza at the heart of Santo Domingo, home to the country's museums and an ornate fountain that plays a haunting role in the third crime. If you've stood by that fountain when the pigeons scatter, you already know something of what Sofía feels.
💡 Real-life tip: Best visited early morning when the plaza is quiet and the light is soft.
Los Tres Ojos · Station Four
Three underground lakes of impossible cobalt blue, formed thousands of years ago in a collapsed limestone cave system. The Taíno used this site ceremonially long before the Spaniards arrived. In the novel, the pattern accelerates here.
💡 Real-life tip: Shout inside the caves. The echo returns three seconds later—deeper, older, changed.
Zona Colonial · The heart of the novel
Five centuries of history pressed into every stone. Cobbled streets laid over older streets. Buildings repaired and re-repaired since Columbus's brother walked here. The Zona Colonial is not a setting in this book. It is a character.
💡 Real-life tip: Walk it at dusk. That's when the novel truly makes sense.
El Malecón · Sofía's dawn
Santo Domingo's oceanfront boulevard, where Sofía runs at dawn trying to outpace her insomnia. The Malecón is the spine of the city—where the wind carries salt and diesel, and every dominicano has memories.
💡 Real-life tip: At sunrise, watching the ocean go from black to grey to the particular washed-out gold of early morning light on water, you'll understand Sofía's chapter openings.
Samaná · The epilogue
Three months after the flood. Playa Rincón. Palms, quiet sand, a horizon that finally belongs to survivors. We'll say no more. 🤐
💡 Perfect for the book club vacation mood board.
Character Analysis
The pieces on the board 🔍
Sofía Méndez
The detective · Twelve years on homicide
Sofía carries the weight of one unsolved case—a child she couldn't save five years ago. Her insomnia, her obsessive attention, and her refusal to trust easily all stem from that failure. Throughout the novel, she confronts not only a killer but her own limits: how far she'll go, who she'll believe, and what she's willing to see even when it involves people she trusts. She isn't the perfect heroine. She's exhausted, obsessive, brilliant, and unmistakably human.
Fernando Reyes
The antagonist · Physician, philanthropist, unseen
Respected doctor. Foundation director. His face appears in every gala photograph. Fernando represents the terrifying premise of the book—that evil can hide inside respectability. He believes his violence is purification. He never raises his voice. He never doubts himself. And no one sees him for what he is.
Camila Ruiz
The journalist · Looking for her brother
Camila's investigation runs parallel to Sofía's, driven not by procedure but by love. She refuses to let her brother Miguel become another statistic. Her arc asks: what does justice look like when institutions fail the people you love? Grief that sharpens into purpose. Journalism used as an act of devotion.
Ana Reyes
The wife · Twenty-two years of watching
Ana's silence is not innocence. Her decision to finally act, after decades of watching, is one of the novel's most quietly devastating moments. She represents the impossible arithmetic of complicity and eventual courage. She reminds us that the people closest to violence often know first. And sometimes, they act.
Carlos Díaz
The son · The one leaving breadcrumbs
Young police officer. Fernando's estranged son. Carlos knew. He always knew. His arc is about the impossibility of speaking directly against a father whose reach is institutional—and the quieter way he chooses to leave a trail for Sofía to find. He inherits nothing but the burden of his father's name.
Milton Daniel Taveras
The partner · Three steps behind her at every scene
Sofía's trusted partner. Steady, quiet, always there. To say more would spoil one of the novel's central turns. But watch him carefully. Everything is there from the first page. The person you trust absolutely is the person you cannot see clearly.
The ones the water took
Mateo · Miguel · Marcos · Martín · Marcel
The chorus of missing young men whose posters no one takes down. Each of them had a life, a family, a Sunday phone call that stopped happening. The novel refuses to treat them as statistics. Their names carry the weight of every young Dominican whose face appears on a light pole and is quietly forgotten.
Fun Facts
Fun facts to shine at book club ✨
🌊 The November 4th flood really happened. While Marielle was writing the final act, Santo Domingo experienced its worst flooding in a decade. The storm made its way into the book.
🏛️ Every location in the novel is real. Marielle walked every single one during the writing process, often at hours when the tourists were gone.
💙 Cobalt 12 is a fictional pigment. But its chemistry, weight, and behavior in water are based on real historical dyes used in colonial-era religious paintings.
⛪ The killer's pattern follows the Stations of the Cross. Marielle spent weeks researching Catholic iconography and colonial religious practices to build the killer's theology accurately.
📱 The book was written while Marielle led a telecommunications company. Chapters were drafted between meetings, on weekends, and during late nights—the way most first novels are actually made.
🍷 The Between the Wines Book Club shaped this novel. Long before it existed as a book, Marielle brainstormed twists over dinners with the BTW girls. Some of them appear in the acknowledgments.
🎧 Written to psychological thriller soundtracks. Playlists included scores from Mare of Easttown, The Killing, and True Detective season one.
📚 Marielle read hundreds of thrillers before writing her own. After years of asking herself "what would I do differently?", she finally answered.
🇩🇴 One of the first psychological thrillers written in English by a Dominican author, set entirely in Santo Domingo. A category almost empty—until now.
🔪 A second novel is already in progress. Marielle's next thriller takes place on a different Dominican island. Expect the water to return.
For the Club 🍷
Book club discussion questions
Pour the wine first. These are going to spark some debates. ⚠️ Contains spoilers.
- On silence as complicity. Ana watched Fernando for twenty-two years before acting. Was her silence a form of survival, complicity, or something else entirely? Could you have done differently in her place?
- On institutional failure. The killer operated in plain sight for years, protected by his reputation, his foundation work, and his wealth. What does the novel say about how institutions fail to see what's in front of them?
- On Sofía's obsession. Sofía carries the failure of Rafael's case for five years. Is her insomnia a sign of trauma, of dedication, or of both? Does her refusal to let go make her a better detective or a broken one?
- On the killer's theology. Fernando believes he is purifying Santo Domingo. How does the novel treat the intersection of faith and violence? Can conviction ever justify what he does?
- On Carlos's choices. Carlos knew about his father but chose to leave breadcrumbs for Sofía rather than confront the truth directly. Was this cowardice, strategy, or a form of moral courage in the only way available to him?
- On the twist of Taveras. When did you first suspect Taveras? Was there a moment that changed how you saw earlier scenes? Discuss how the author planted clues without giving him away. 👀
- On Santo Domingo as a character. The Zona Colonial, the Malecón, the cistern beneath the Alcázar—the city shapes every crime and every discovery. How does location function beyond setting in this novel?
- On the missing boys. Mateo, Miguel, Marcos, Martín, Marcel. What did the pattern of names suggest to you? What does the novel say about young men who disappear without justice?
- On the flood. When the November storm arrives, everything Fernando controlled is undone by water. Is nature acting as justice? As chaos? As something older than either?
- On the ending. Miguel survives. Camila finds him. Sofía closes the case. But nothing is resolved cleanly. Is this the right ending for the story? What would you have changed?
- On what comes next. If a sequel follows any of these characters, who do you want to see again? Whose story feels most unfinished? 🚪
Between the Wines Verdict
Should you enter the water?
🍷🍷🍷🍷🍷
5 / 5 glasses — a debut worth every sip
✅ Read it if you love…
Atmospheric slow-burn thrillers, multiple POVs that lock into each other like puzzle pieces, unreliable partners, morally complicated female leads, and settings that function as full characters.
⚠️ Keep in mind…
It's a slow burn that rewards patience. If you need a bombshell twist every 20 pages, this one plays a different game: the ground shifts gradually beneath you until you realize it's been shifting the whole time.
📚 For fans of…
Freida McFadden's misdirection, Lisa Jewell's interlocking timelines, Alice Feeney's unreliable framing, and any thriller where the setting refuses to fade into the background.
A thriller written in English by a Dominican author, set entirely in Santo Domingo, that treats the city with the reverence it has always deserved.
And remember: some currents pull you toward the truth. Follow them. 🌊
Get the Book →Read Next 📚
Books to read after this one
Still hearing the water? Keep that energy going with these.
If you loved the atmosphere
The Sanatorium
by Sarah Pearse
Isolated setting, slow-burn tension, and a detective who can't let go. The Swiss Alps replace Santo Domingo but the atmospheric grip is the same.
🏔️ Cold instead of tropical, still relentless
If you loved the twist
The Housemaid
by Freida McFadden
Where trust and manipulation converge—and the ground beneath the reader keeps shifting. McFadden gives you all the information in the wrong order and lets your brain build a story that isn't real.
🧹 Fast, twisty, unputdownable
If you loved the multiple POVs
None of This Is True
by Lisa Jewell
Interlocking narratives, moral ambiguity, and an ending that lingers. Jewell knows how to make the reader lean in and lean back at the same time.
🎙️ Podcast-flavored dread
If you loved the detective
Rock Paper Scissors
by Alice Feeney
Unreliable narrators taken to another level. If you liked how Marielle kept you doubting your instincts about Taveras, Feeney will finish the job.
🎭 Marriage as psychological warfare
If you loved the Caribbean setting
In the Time of the Butterflies
by Julia Alvarez
Not a thriller, but essential Dominican fiction. If Unsolved Waters made you fall in love with the DR as a setting, Alvarez's masterpiece will take you deeper into the country's soul.
🦋 Dominican literary heritage
If you want more from this world
The Influencer
by Marielle E. Suárez (coming soon)
Marielle's second thriller takes place on Isla Saona—another Dominican island, another set of secrets the water keeps. Expect familiar echoes and brand new dread.
🏝️ Second novel · In progress
