Sweat And Sin. Undertow Sins, #19

"She came to pay her father's debt. He collected in a currency she never agreed to - and one she couldn't stop spending."For six years, Rhett Calloway lived for one single purpose: absolute, unyielding vengeance. His brother's life was stolen in a blood-soaked underground fighting ring run by Lyle Mercer, a corrupt executive who controls the Savannah River docks. When Mercer defaults on a strategic debt, Rhett demands a payment that cuts straight to the bone: three months of his daughter's time, trapped inside his gritty boxing warehouse known as "The Yard."Dagny Mercer is an expert orthopedic physical therapist, but she is no innocent lamb led to the slaughter.
Behind her clinical precision lies a childhood forged in fear, survival, and her father's violent conditioning. She enters Rhett's hostile territory willingly, not because she is broken, but because she is carrying a weapon of her own. Hidden in her bag is a waterproof drive containing the definitive, terrifying footage of the fight that killed Rhett's brother-evidence she stole but was too paralyzed by terror to ever expose.
Inside the stifling, humid cage of the gym, a brutal psychological chess match begins. Rhett expects a fragile princess he can shatter to ruin her father. Instead, he finds a woman who doesn't flinch at pain, tracking his vulnerabilities with the same clinical accuracy he uses to break her down. Physical proximity becomes an addictive, toxic current as they push each other to the absolute edge of endurance.
But when a devastating Category 2 hurricane slams into Savannah, the grid goes dark and the doors are sealed. Trapped together in the absolute silence of the storm's eye, the walls of deception collapse. When Rhett uncovers the secret Dagny carried into his domain, his entire architecture of revenge is shattered. From the humid shadows of an illegal ring to a raw, storm-swept redemption, Sweat and Sin is a breathtaking, dark romantic thriller about two damaged souls who must decide if they will destroy each other-or become the only sanctuary left in a world built on sins.