Mercy by Jodi Picoult
Cameron MacDonald has spent his life guided by duty. As the police chief of a small Massachusetts town that has been home to generations of his Scottish clan, he is bound to the town's residents by blood and honor. Yet when his cousin Jamie arrives at the police station with the body of his wife and the bald confession that he's killed her, Cam immediately places him under arrest. The situation isn't as clear to Cam's wife, Allie. While she is devoted to her husband, she finds herself siding against Cam, seduced by the picture James paints of a man so in love with a woman that he'd grant all her wishes ...even the one that meant taking her life. Into this charged atmosphere drifts Mia, a new assistant at Allie's floral shop, for whom Cam feels an instant and inexplicable attraction. While he aids the prosecution in preparing the case against Jamie, who killed his terminally ill wife out of mercy, Cam finds himself betraying his own wife.