A death in the woods draws Castle back to a terrifying and defining event in his childhood. Investigation leads to obsession, as he attempts to unearth answers that have eluded him for decades, all while Beckett faces a crossroads of her own.

Beckett and the 12th Precinct look into the murder of an English as a Second Language student. But when the victim's class won't talk to the police, Castle goes undercover as a French Canadian immigrant and learns that the victim was more than he seemed.