Former Marine Daniel "Hondo" Harrelson is tasked to run a specialized tactical unit in Los Angeles.
The team must find four escaped convicts before a rival team finds them; Hondo's leadership is called into question when Street flagrantly disregards protocol.
Newcomer Jim Street jeopardizes his spot on Hondo's team; the team searches for a ruthless drug trafficker who is using immigrants as couriers.
After a domestic bomber dies in an explosion, the SWAT team races to find the man's partner before more devices detonate; Hondo reaches out to his former team leader.
Home invasions are committed by SWAT imposters; Hondo suspects the burglarized families are hiding something; Deacon and Luca are assigned to protect a visiting professional hockey player who is receiving death threats.
Hondo allows newbie Jim Street to go under cover to bust a ruthless trafficker; Hondo visits the teenager recently shot by a former member of the SWAT team.
Hondo's imprisoned childhood friend asks him to protect his son from gang violence; the team encounters a new local crime outfit; Luca's grandfather, a S.W.A.T. legend, passes away, and Luca struggles with his grief and a painful family secret.
The team must work during Christmas vacation when a drug cartel's cache of gold bars is stolen; Jessica approaches the president of the police commission with her ideas on how to improve the S.W.A.T. division.
When a misconduct complaint filed against Hondo gets him taken off active duty, Deacon steps up to lead the team in finding a robbery crew that is hitting marijuana dispensaries.
The SWAT team tries to rescue civilian hostages during a prison riot; Hondo suspects an ulterior motive behind the uprising; Deacon's wife stops by the headquarters to celebrate Deacon's 10th anniversary with the SWAT division.
Hondo teams up with an old DEA friend to unmask the secret leader of a drug smuggling ring; Jessica begins implementing her new law enforcement community initiatives.
Hondo and the team join forces with the FBI on a manhunt to find a militia group planning a domestic terror attack; Jessica's new police initiatives move forward; she braces herself for the negative impact those initiatives could have.
Hondo and Jessica's secret relationship comes to a crossroads when the president of the police commission discovers their affair; Hondo and the team assist with the federal investigation to bring in an undocumented fugitive.
The team goes on the hunt for a serial killer who escaped justice two years prior by faking his death; Hondo worries that the team's former leader is spiraling into depression in the aftermath of being fired from the department.
Hondo's informant friend is killed while seeking information for a joint SWAT and FBI task force; when the FBI task force leader acts erratically, Jessica worries the woman's behavior will endanger the team in the field.
A young heiress is kidnapped for ransom; the team goes on a citywide search to bring her home before she is harmed; the team worries that Mumford is moving too fast when he announces he's getting married for the fourth time.
As the team works to de-escalate a hostage situation, the mission takes a dangerous turn, which impacts the team; Street tires of his complicated romantic entanglements and agrees to let Chris make over his online dating profile.
Hondo confronts his resentment toward his ailing father when he and his sister try to convince their dad he's no longer well enough to live alone; Mumford intends to make Chris a surprising offer.
Jim Street debates whether or not his mother should live with him upon her release from prison; Hondo and the team are assigned to protect a high-profile Russian journalist who is visiting Los Angeles.
Hondo's life and career are threatened when his off-the-books surveillance of his godson's kidnapper is discovered; Street has trouble acclimating to his newly paroled mother.
Hondo and Deacon must evade a gang of armed mercenaries hunting them in the mountains following an ambush; Chris oversteps his boundaries in an attempt to help a female SWAT trainee who she suspects isn't being evaluated fairly.