Tough, relentless Jack Malone heads the Missing Persons Unit of the FBI. And this season the dedicated investigators of the MPU have a particularly important missing person to locate: Jack Malone, who disappears after going solo on a perilous case. The search for lack is only one of many high-impact cases involving the mysteriously vanished, from a waitress who won $32 million in the lottery to an extreme fighter to a mall Santa Claus -and a case uniting the MPU with the Las Vegas-based investigators of CSI: Crime Scene Investigation. But the drama and suspense aren't limited to other people's lives. Agent Samantha Spade faces single motherhood. And Jack's history of warrantless searches, witness intimidation and violation of FBI case protocol in pursuit of justice may finally cost him his career.