Nash pursues a deadly arsonist who torches a church and the only witness is Angel. Caitlin investigates Evan on a police brutality charge, probing into his past. Nash's friends and family plan a surprise birthday for him.

Nash finds himself defending Caitlin when she's the main suspect for a murdered CIA agent connected to her mysterious past. Joe begins working out with the trainer from hell. Cassidy and Nick enter a tango dance contest.