As Mark, Naomi and Ellie work together to make sure Isaiah has the best birthday ever, complicated feelings arise. Claire starts to form a bond with Matthew and continues down a path of no return by taking her research to a whole new level.

Mark goes on a date with Naomi, but Eleanor realizes his motives might not be as sincere as they seem. Naomi and her partner, Ben, close in on their suspect, Claire, who has found a terrifying new way to advance her research.

Desperate for help, Mark turns to his faith for guidance, but Eleanor decides to help him instead, risking her life. Naomi is visited at work by a formidable new Interpol agent and Isaiah gets heartbreaking news.