The Good Samaritan (No. 106)

The entire FBI team is under investigation as internal affairs tries to find the mole. Elsewhere, Red is missing and conducts his own investigation into who betrayed him. Meanwhile, a serial killer from Liz's past, "The Good Samaritan" strikes again. Liz is allowed to join the hunt for the killer as Cooper knows Red will likely reach out to help knowing how much this unsolved case means to Liz.