Isla Aurelia Montclair survives on borrowed grace—a scholar living under the Windsor name, raised beside Elodia Ara Windsor as her sister and sworn secret. Their bond is unbreakable, or so Isla believes. But fate is rarely kind. One night changes everything when Isla meets Zach Sebastian Montgomery—the man promised to Elodia. What begins as a fleeting encounter becomes a dangerous pull neither of them can resist. As secrets unravel and hearts betray their vows, Isla finds herself caught between the sister she would die for and the man destiny seems determined to claim. But in the end, someone must bleed for borrowed grace.