Fagin

S4 E21: When the team is called to an in progress bank robbery, they come across Detective Hailey Upton (guest star Tracy Spiridakos) trying to take over the crime scene with her Robbery Homicide unit butting heads with Voight (Jason Beghe) in the process. As the robberies continue to be executed around the city, Lindsay (Sophia Bush) is forced to make a decision in the heat of the moment, revealing a surprising suspect behind the mask. While working on the case at the district, Upton is shocked to come across Platt (Amy Morton), who has a special connection to her past.