S4, E6: When the investigation of a missing girl is linked to a convicted murderer who has had a past with 15 Division, it’s all hands on deck. Detective Luke Callaghan comes in to help bring the copycat abductor to justice and get the missing girl home safe. While most of the officers are out looking for witnesses, Luke and Chris discover that the imprisoned convict himself may prove to be a useful ally in the investigation. And when Gail is forced to confront her worst fear in order to help solve the case, her recent infidelity is pushed into the harsh light of day. Back at 15, Traci is seconded to Guns and Gangs to work with Steve Peck. Her emotional response to this specific case pushes her to realize that she must move out of the past, and start trying to get over Jerry Barber. Meanwhile, Swarek and Andy work together to locate the copycat -- coming face-to-face with their unspoken past, and the real reason for their breakup.