The SWAT team works with Lieutenant Piper Lynch, a senior LAPD Hollywood Division officer, when the mayor assigns her to oversee city departments joining forces to stop a serial bomber using drones as detonation devices. Just as Hondo settles into legal guardianship of his teen charge, his home life becomes more complicated when his estranged father unexpectedly moves in.
Lynch pulls the SWAT team's focus when the mayor tasks her with enacting a departmental review of the squad right as they pursue the unstable and dangerous fugitive leader of an infamous doomsday cult. Luca asks the team to invest in his new passion project-a Guatemalan food truck.
The SWAT team bumps heads with Lynch when she signs them up for an off-book undercover operation to take down a local gang printing counterfeit money, without giving them enough time to prepare for the mission. Tensions rise at home for Hondo as his parents' strained relationship becomes worse.
Deacon's family gets caught in the crosshairs of a drug cartel when the team aims to bring down its leader; Hondo receives troubling news regarding his father; Tan is forced to go before an internal review board due to his girlfriend's indiscretion.
Street reconnects with his estranged foster brother to help a joint investigation between SWAT and the Long Beach PD when criminals steal a mass arsenal of LAPD assault rifles. Hondo finds himself at odds with his father over the elder man's declining health. Luca is overwhelmed when the entire team reconsiders becoming investors in his food truck.
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. The SWAT team searches for an abducted Middle Eastern human rights activist. Luca's food truck business hits a snag. Street worries that dating Captain Hick's daughter, Molly, will negatively impact his career.
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.
The SWAT team engages in tense negotiations with a family that takes a local officer hostage when they're evicted from their home due to eminent domain. Also, Hondo reflects on his personal life choices as he helps his father through a medical crisis and Chris' relationship with Kira and Ty reaches a critical juncture.
The SWAT team joins forces with the Los Angeles Organized Crime division to recover an officer abducted during a failed undercover operation. Also, Chris struggles with how to comfort the kidnapped officer's parents when she is restricted from giving them certain details of the investigation.