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.

Mark and Eleanor turn to Claire and Peter for help, but soon realize they may have a plan of their own. Meanwhile, Naomi and her new partner, Debra, make strides in their case, and Naomi uncovers a huge secret. Season finale.