When the SWAT team is called in to work on their day off to end a hostage situation, they discover one of the captives is a wanted felon. When Hondo saves his sister after she's been roofied at a nightclub, he uses his day off to hunt a serial rapist.

The SWAT team races to locate the next place a lone gunman will strike while he is at large in Los Angeles. Also, Hondo takes some time away from the team to pursue an investigation that hits close to home, and Jessica is presented with an unexpected opportunity.

The Harrelsons engage in a tense family reunion when Hondo’s older sister, Winnie, begrudgingly arrives in Los Angeles to see their sick father for the first time in decades. Also, the SWAT team searches for an abducted Middle Eastern human rights activist; Luca’s food truck business hits a snag; and Street worries that dating Captain Hick’s daughter, Molly, will negatively impact his career.

The SWAT team searches for a link between the seemingly unconnected victims of a lone gunman targeting women. Also, Luca assists with a homicide investigation in his neighborhood; Lieutenant Lynch pushes Chris to do a news interview; and Hondo reaches a juncture in his relationship with Nichelle.

SWAT searches for a group of extremists carrying out coordinated attacks against local businesses. Also, Deacon and his wife, Annie, find themselves at odds when Annie wants to enroll their daughter, Lila, in private school.

Mumford returns to work a 15-year-old cold case that holds a personal connection and leads to the discovery of a dangerous drug ring. Hondo is leery of Leroy’s motives when he discovers the recent parolee is seeking funding for a new business venture with his son, Darryl.

During a trip to Bangkok to train alongside Thailand’s premiere S.W.A.T. team, Hondo and his former military buddy Joe (guest star Sean Maguire) stumble upon a wide-ranging heroin operation with ties to Los Angeles and find themselves on the run from a powerful drug kingpin.