S3, E11: After a luxury condo is robbed, the team is shocked to learn that not only was the family fast asleep when the crime occurred, but their teenaged daughter was violated during the invasion as well. Voight (Jason Beghe) consults Jimmy (guest star Steven R. McQueen) from Firehouse 51 to confirm his suspicion that the family was knocked out by a powerful gas, and Lindsay (Sophia Bush), Halstead (Jesse Lee Soffer), Atwater (LaRoyce Hawkins) and Ruzek (Patrick Flueger) go undercover to seek out the perpetrators. Meanwhile, Voight tries to help a former acquaintance get back on his feet, and Platt (Amy Morton) and Mouch (guest star Christian Stolte) receive disappointing news regarding their upcoming wedding.