Hondo reunites with an old flame, FBI Special Agent Elle Trask, when the SWAT team works with the FBI to bring in a separatist group with weapons-grade plutonium. Also, the SWAT team worries they will lose an annual law enforcement charity competition to the Los Angeles Fire Department.

As the team works to stop a violent attack on the city, they're forced to confront the group responsible for the death of a team member. Hondo and Leroy disagree on how to handle a challenge to Darryl's fledgling business.

When four escaped prisoners take control of a courthouse with Hondo and Deacon inside but unarmed, the two race to save the lives of innocent civilians while trying to avoid detection themselves. Street visits his mother in the hospital and faces a pivotal decision.