Starting over isn't easy, especially for small-town guy John Nolan who, after a life-altering incident, is pursuing his dream of being a police officer. As the force's oldest rookie, he’s met with skepticism from some higher-ups who see him as just a walking midlife crisis. Throw in a workplace romance, a hostage situation, and some tough love from their new training officers, and the latest Los Angeles police rookie class has an uphill battle ahead of them.

Nolan is given some life-changing news and invites Grace over for a homecooked meal in his newly remodeled kitchen. Meanwhile, each unit is tasked with following up on dormant cases in the hopes they can uncover new leads.

Officer Nolan and the LA division of the FBI enlist the help of FBI trainee Simone Clark when one of her former students is suspected of terrorism following an explosion at a local power station.