Part 1 of 2. When Chandler, Miles and the team attend the christening of Miles's daughter, Martha, a fox runs through Whitechapel with a human arm inside its mouth. Soon, more body parts from the same victim are washed up by the river.

When a babysitter is murdered and a dangerous patient and former Whitechapel resident escapes from a psychiatric unit, the area is hit by a series of terrifying events. Fearing that a spree killer is on the loose, Chandler, Miles and the team must act fast to prevent more deaths. Meanwhile, Chandler's quest to bring in a suspect alive jeopardises his relationship with Miles.