The team searches for missing 15-year-old Ryan Wallace who was obsessed with the safety of his school after losing a parent and watching the towers on 9/11 fall. Martin and Vivian both return from medical leave.

The backpack and ID of missing college coed Skye Petersen are suddenly dropped off at a thrift store seven years after Jack--and ultimately the legal system--determined she was murdered by her married professor with whom she'd just ended an affair.