When the Bough Breaks

A woman who is an illegal immigrant is found dead in a manhole, prompting Castle and Beckett to uncover a dark secret about a successful doctor, and a possible connection between his son, and that of the victim. At the same time, Castle's first book based on Beckett, Heat Wave, is released to rave reviews, and he is offered the writing opportunity of a lifetime, causing him to struggle with the fact that accepting the new gig would end his partnership with Beckett.