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Double Progression: A Kelsey James Fitness Mystery: Book Two
A devoted wife. A chilling discovery. A personal trainer caught in a dangerous game of secrets.
Kelsey James knows all about strength, perseverance, and staying focused under pressure. As a seasoned personal trainer, she’s helped countless clients rebuild their bodies—and their confidence. But when her client Jennifer confides that her husband has gone dark during a routine business trip, Kelsey’s instincts kick in.
His story doesn’t add up.
The office he claims to be visiting? Closed.
His phone location? Disabled.
His job? Terminated.
And a suspicious $500,000 bank transfer suggests he’s not just hiding something—he’s running from it.
What starts as friendly concern spirals into a high-stakes investigation, pulling Kelsey into the heart of a domestic thriller filled with lies, betrayal, and dangerous truths. As the facade of a picture-perfect marriage shatters,, Kelsey races to uncover the truth.
Sharp, suspenseful, and impossible to put down, this domestic thriller will leave readers questioning just how well we really know the people closest to us.
Kelsey James knows all about strength, perseverance, and staying focused under pressure. As a seasoned personal trainer, she’s helped countless clients rebuild their bodies—and their confidence. But when her client Jennifer confides that her husband has gone dark during a routine business trip, Kelsey’s instincts kick in.
His story doesn’t add up.
The office he claims to be visiting? Closed.
His phone location? Disabled.
His job? Terminated.
And a suspicious $500,000 bank transfer suggests he’s not just hiding something—he’s running from it.
What starts as friendly concern spirals into a high-stakes investigation, pulling Kelsey into the heart of a domestic thriller filled with lies, betrayal, and dangerous truths. As the facade of a picture-perfect marriage shatters,, Kelsey races to uncover the truth.
Sharp, suspenseful, and impossible to put down, this domestic thriller will leave readers questioning just how well we really know the people closest to us.
Kindle Edition
Published October 28, 2025
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Displaying 1 - 15 of 15 reviews
October 13, 2025
Kelsey James isn't just a great personal trainer. She's as skilled as they come. Sure, she'll demand those burpees, push you to finish out that set of hammer curls, spot you for those bench presses. You'll leave encouraged and thoroughly butt-kicked after every session. But if you've got issues at home or elsewhere, there's also a good chance she'll take a crack at being your personal investigator, too.
Kristina Fox's Double Progression, her second Kelsey James Fitness Mystery, begins with our main character still savoring the satisfaction of her first case, in which she helped a client solve a grisly murder. Ready to lunge into another mystery, we meet Jennifer Miller: established client, friend, entrepreneur, mother of three, and wife to a seemingly perfect husband. If he would only spill the beans about what he's been up to. Grayson Miller has always gone away for business trips, as anyone would expect of a successful hedge fund manager, but the trips are becoming longer, and the laundry and aromas he returns with don't jive with his stated destination. Inquiries about how this-or-that trip went are met with deflections or vague, one-word answers.
With Kelsey on the case, it's soon discovered that the office he claims to be visiting is not only closed for remodeling, but he doesn't even work for that company anymore. What at first seems like an open-and-shut case of infidelity quickly spirals into a twisty tale of organized crime, undercover law enforcement, and stakeouts. For a personal trainer moonlighting as an investigator, Kelsey is surprisingly resourceful, using everyday objects and services with such skill that she's about as effective as the law enforcement operating alongside her.
A heaping helping of exercise and cooking talk rounds everything out. You'll stand next to Kelsey and her co-workers as they run through exercises tailored for each client, and sit with the gang at dinner, complete with mouthwateringly vivid descriptions of what everyone ordered (sometimes down to the garnish). Crafty readers could probably put together a nice workout routine, not to mention a decent menu.
Fox’s writing is refreshingly accessible, with a colorful cast of characters at whom she’s unafraid to poke fun. She precariously straddles the line between crime fiction and farce, evoking an unlikely combination of Janet Evanovich and P.G. Wodehouse. Double agents, triple agents, safehouses, medical emergencies, unexpected family connections, murder, and even adult twins swapping places to conduct recon in each other's homes (all revealed at the most convenient times) are just a few of the exciting twists and fake-outs employed in Double Progression. Readers will find a lot to love in this lighthearted and fun crime mystery.
Kristina Fox's Double Progression, her second Kelsey James Fitness Mystery, begins with our main character still savoring the satisfaction of her first case, in which she helped a client solve a grisly murder. Ready to lunge into another mystery, we meet Jennifer Miller: established client, friend, entrepreneur, mother of three, and wife to a seemingly perfect husband. If he would only spill the beans about what he's been up to. Grayson Miller has always gone away for business trips, as anyone would expect of a successful hedge fund manager, but the trips are becoming longer, and the laundry and aromas he returns with don't jive with his stated destination. Inquiries about how this-or-that trip went are met with deflections or vague, one-word answers.
With Kelsey on the case, it's soon discovered that the office he claims to be visiting is not only closed for remodeling, but he doesn't even work for that company anymore. What at first seems like an open-and-shut case of infidelity quickly spirals into a twisty tale of organized crime, undercover law enforcement, and stakeouts. For a personal trainer moonlighting as an investigator, Kelsey is surprisingly resourceful, using everyday objects and services with such skill that she's about as effective as the law enforcement operating alongside her.
A heaping helping of exercise and cooking talk rounds everything out. You'll stand next to Kelsey and her co-workers as they run through exercises tailored for each client, and sit with the gang at dinner, complete with mouthwateringly vivid descriptions of what everyone ordered (sometimes down to the garnish). Crafty readers could probably put together a nice workout routine, not to mention a decent menu.
Fox’s writing is refreshingly accessible, with a colorful cast of characters at whom she’s unafraid to poke fun. She precariously straddles the line between crime fiction and farce, evoking an unlikely combination of Janet Evanovich and P.G. Wodehouse. Double agents, triple agents, safehouses, medical emergencies, unexpected family connections, murder, and even adult twins swapping places to conduct recon in each other's homes (all revealed at the most convenient times) are just a few of the exciting twists and fake-outs employed in Double Progression. Readers will find a lot to love in this lighthearted and fun crime mystery.
October 9, 2025
Double Progression brilliantly intertwines the worlds of fitness and mystery. Kristina Fox crafts Kelsey James as more than a trainer she’s a metaphor for resilience and endurance. The gym scenes are vividly written, capturing the discipline, rhythm, and repetition of training as a mirror to Kelsey’s determination to uncover the truth. It’s a clever, adrenaline pumping read that turns the treadmill into a track toward justice. Fans of fitness themed fiction will find it grippingly motivational.
December 10, 2025
Kelsey James, fitness instructor extraordinaire and part-time amateur sleuth, is busy training clients at the gym when one of them asks her for help. Jennifer Miller’s husband, Grayson, is on one of his usual business trips to Seattle, yet this time, in three days, she’s only spoken to him once. She’s sure something untoward is going on, and she asks Kelsey to look into it for her. Not long into the investigation, a dead body turns up in a hotel room booked under Grayson’s name, and Kelsey starts to believe she’s landed into something worse than she can imagine. The Miller family may not be as squeaky clean as they appear, and as the secrets and lies come to the surface, Kelsey gets more than she bargained for. Who can she trust? You’ll have to read Kristina Fox’s Double Progression to find out.
I discovered Kelsey James in Kristina’s first book, Time Under Tension, and was anxiously waiting for the sequel. I was not disappointed. The twists and turns in this narrative are jaw-dropping. I found myself reading well into the night as I had to know what was going on. Kelsey James is a fantastic character; she could be like any of the personal trainers at your gym, except she’s so much better. Even though Double Progression is book two in the series, you don’t have to read book one first, but definitely add it to your must-read list anyway. I give Double Progression 5 out of 5 stars, and I’m already excited for book three in the series.
I discovered Kelsey James in Kristina’s first book, Time Under Tension, and was anxiously waiting for the sequel. I was not disappointed. The twists and turns in this narrative are jaw-dropping. I found myself reading well into the night as I had to know what was going on. Kelsey James is a fantastic character; she could be like any of the personal trainers at your gym, except she’s so much better. Even though Double Progression is book two in the series, you don’t have to read book one first, but definitely add it to your must-read list anyway. I give Double Progression 5 out of 5 stars, and I’m already excited for book three in the series.
October 9, 2025
This novel hits all the marks of a top tier domestic thriller marital secrets, financial deception, and a woman’s intuition steering her into dangerous territory. Kelsey’s dive into her client’s nightmare feels personal and believable. The pacing is sleek, the twists unexpected, and the ending delivers that Oh my God gasp. Double Progression feels like Gone Girl met a gym membership and refused to skip leg day.
October 9, 2025
Double Progression is about empowerment through awareness. Kelsey James is not just solving a mystery she’s reclaiming agency in a world that underestimates her. Fox uses the fitness metaphor masterfully. building strength isn’t only physical, it’s emotional and moral. Watching Kelsey transform from a professional trainer to a determined truth seeker feels empowering for any reader who’s ever doubted their instincts.
October 9, 2025
Kristina Fox’s writing style is clean, visual, and tension driven. The pacing rarely falters, balancing between emotional introspection and sharp plot turns. Kelsey’s voice feels authentic her professionalism, compassion, and skepticism align naturally. While some thriller tropes appear, Fox refreshes them through the fitness milieu, adding originality. It’s not just a page turner, it’s a tightly designed exercise in character driven suspense.
October 12, 2025
Reading Double Progression felt like watching a sleek Netflix thriller. Fox’s descriptive rhythm makes each chapter feel like a scene. the echo of running shoes, the hum of gym machines, the silence of suspicion. You can practically see the tension on screen. Kelsey is a lead actress waiting to happen resilient flawed and deeply human. This story would translate beautifully to film or limited series.
October 15, 2025
Kristina Fox’s Double Progression stands out for giving agency to women in a genre often dominated by male saviors. Kelsey James doesn’t wait for the cops she investigates, questions, and persists. Through her, Fox dismantles the stereotype of the passive female by making her intellect, intuition, and empathy the driving forces of the plot. It’s a story about reclaiming control body, mind, and truth.
December 18, 2025
A gripping no escaping thriller read!
From the very first page it was tense, every chapter raising the stakes. Every decision carried consequences and nothing felt safe. The characters were raw and flawed - just the way I like them. 🔥The twists and turns hit hard leaving my heart racing and my eyes completely glued to the pages - in this case my screen…🤣😂 Such a gripping no escaping thriller read you will have to pick up and read. Now.
From the very first page it was tense, every chapter raising the stakes. Every decision carried consequences and nothing felt safe. The characters were raw and flawed - just the way I like them. 🔥The twists and turns hit hard leaving my heart racing and my eyes completely glued to the pages - in this case my screen…🤣😂 Such a gripping no escaping thriller read you will have to pick up and read. Now.
December 19, 2025
Double Progression delivers nonstop suspense from the very first chapter. The mystery is smartly constructed, and each new discovery raises the stakes in a way that kept me completely invested. Kelsey James is a strong, believable lead whose determination makes the story feel real and urgent. The twists are well earned, and the tension never lets up. An excellent domestic thriller that truly keeps you guessing.
October 9, 2025
Double Progression in two sittings What fascinated us most wasn’t just the mystery it was how Fox tied themes of trust, identity, and perseverance into every scene. Kelsey’s compassion contrasts beautifully with Jennifer’s desperation, creating an emotional dynamic that sparks deep discussion about what we’d do in similar situations. It’s the perfect blend of suspense and substance.
October 12, 2025
I didn’t expect to get hooked this quickly, The story starts small a missing husband but unravels into a wild chase of secrets and money. Kelsey is such a likable character, strong without being over the top. I liked how Fox kept things fast paced yet emotionally grounded. If you want something that’s easy to read but keeps you guessing, this is it.
October 14, 2025
I appreciated how Double Progression flips expectations. The investigator isn’t a detective or journalist it’s a personal trainer That fresh angle changes everything. Kelsey’s methods rely on observation, empathy, and intuition instead of police protocol. The clues are cleverly layered, and the stakes rise naturally. Fox’s handling of tension rivals seasoned crime writers.
October 15, 2025
I found Double Progression incredibly authentic. The client trainer relationship is captured perfectly the boundaries, the confidences, the trust that can easily blur. Kelsey’s professionalism mixed with human curiosity makes her believable. Fox doesn’t glamorize the industry, she shows its real pressures while using it as a backdrop for a clever, high stakes mystery.
December 18, 2025
A gripping no escaping thriller
From the very first page it was tense, every chapter raising the stakes. Every decision carried consequences and nothing felt safe. The characters were raw and flawed - just the way I like them. The twists and turns hit hard leaving my heart racing and my eyes completely glued to the pages - in this case my screen...lol. Such a gripping no escaping thriller read you will have to pick up and read. Now.
From the very first page it was tense, every chapter raising the stakes. Every decision carried consequences and nothing felt safe. The characters were raw and flawed - just the way I like them. The twists and turns hit hard leaving my heart racing and my eyes completely glued to the pages - in this case my screen...lol. Such a gripping no escaping thriller read you will have to pick up and read. Now.
Displaying 1 - 15 of 15 reviews