The SWAT team tries to determine the next diamond dealer to be robbed by a group of highly organized thieves executing heists across downtown Los Angeles. When Hondo is emotionally affected by a suspect’s death during the case, he seeks comfort from his mother. Street worries that his SWAT training academy instructor has a personal vendetta against him. Chris contemplates an unorthodox relationship offer from the new woman she’s dating.

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.

Hondo has a tense reunion with a fellow Marine, Ruiz, when the team hunts an escaped convict who was broken out of prison by criminals using stolen military weapons; Chris prepares for a difficult goodbye when her former K-9 partner becomes ill.

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.

The SWAT team searches for thieves who are on the run with a high-tech thermal lance that can cut through almost anything. To find the thieves, SWAT works to identify their target. Also, Chris confronts an imbalance in her relationship with Kira and Ty.