The LAPD, FBI and Interpol work with Monica Stevens in Prague to target high-value terrorists operating within and outside the United States.

When the president visits Los Angeles, the LAPD teams up with the Secret Service to ensure his safety and assess any major threats on their watch list. Meanwhile, Miles's instincts are tested, and Tim takes on a new role.

Nolan makes a quiet arrest, and Lucy and Celina race to rescue a kidnapping victim. Meanwhile, Harper and Lopez help outsmart a killer, and Miles visits a familiar face.

While out in the city, Nolan and Bailey witness a murder in public and immediately spring into action in the hopes of finding the person responsible. Meanwhile, Angela and Wesley have a big life decision that may affect their future.

Lieutenant Grey and the FBI task force enlist the help of an old colleague to uncover a criminal network. Nolan, Miles, Lucy, and Celina respond to a mysterious officer-involved shooting.

Harper and Lucy go undercover in Baja while investigating the murder of two young women. Back in LA, Bradford and the FBI task force assist in the investigation, while Nolan and Bailey navigate their long-distance relationship.

Nolan and Garza lead a high-stakes operation that quickly goes south. Lucy and Tim navigate their relationship when an unexpected visitor shows up. Meanwhile, the team conducts a citywide search for a suspect.

Harper and Miles feel the weight of their recent mistakes, while Harper is tasked with training Miles. Nolan and Celina are dispatched to a robbery call where Nolan encounters a familiar face.

Nolan, Harper and Miles face a dangerous situation when a routine check takes a sudden turn. Meanwhile, Bailey conducts a covert investigation at the Pentagon at the request of Lt. Grey.

Lucy returns to work in the aftermath of the attack. Meanwhile, an unexpected twist hinders the Liam Glasser case, and a familiar face helps the team track down a killer.