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.

Hondo and the SWAT team race to save Buck, their former unit leader, when he goes off grid and they fear he plans to harm himself. Flashbacks reveal the search for Buck, which coincides with one of the team’s most brutal missions, as each team member receives counseling and discusses the untold mental and emotional difficulties inherent to working in SWAT.

As the team races to stop a violent band of armed robbers, the search is complicated by civilians using a public safety app that encounters vigilantism; Street receives difficult news that alters his future.

Following a string of violent home robberies, the team rushes to stop a crew targeting elderly victims; Hondo's longtime friend and former Marine squad leader Danny Wright turns to Hondo for help when his daughter goes missing.

A blackout throws the city into chaos, forcing 20-Squad onto the streets for an emergency patrol day, which quickly escalates when Hondo and team uncover a terror threat.

The abduction and brutal torture of two college football stars puts S.W.A.T. on the trail of a violent drug dealer looking to extract vengeance for a drug deal gone bad, while Deacon’s heroics bring unexpected attention on S.W.A.T.