Hondo suspects an ulterior motive when Nina's estranged husband, US Marshal Eric Wells, requests the S.W.A.T. team’s help with apprehending a fugitive who is robbing drug cargo shipments. Jessica is forced to implement departmental budget cuts. Street makes a heartbreaking discovery about his mother.

The SWAT team races to find a stalker pursuing a social media star, after the online celebrity's dangerous admirer turns a fan event into a shootout that endangers Jessica.

The SWAT team faces difficult reminders of a past school shooting when they receive a warning that a copycat plans to re-enact the crime. As the team races to stop the new threat, they flash back to the day of the tense first mission.

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.

The SWAT team tries to zero in on the next target of a carjacking ring that’s using deadly force to boost luxury vehicles all over Los Angeles. Also, Hondo takes a big step to help his childhood friend’s incarcerated son, Darryl, and SWAT team leader Mumford weighs a major decision.

The SWAT team discovers a new version of PCP with ties to an escaped drug dealer who created a version that ravaged the city decades earlier. Tan’s personal ties to the case emerge when he brings in his mentor, Ben Mosley, the former lead detective on the original drug case, to help. Also, Chris weighs a major decision regarding her romantic relationship with Kira and Ty, and Hondo’s patience is tested by his new familial responsibilities.