While staking out the red-light district of San Diego, the recently demoted Cullen and Tolbeck spot some suspicious activity. Meanwhile, Janice from Dispatch is not happy when Clint, a former flame and co-worker, is brought in as Dispatch's new supervisor.

Cullen is tasked with helping Officer Charles Brock extradite a key witness in the Las Hormigas Cartel investigation but all hell breaks loose at 30,000 feet. Back at Dispatch, Clint begins to shake things up by introducing new technology to the department but not everyone is quite as thrilled. Still in the hotel room, Chief and Gary try to stay occupied while awaiting their target.

Cullen tries to set boundaries as a worse-for-wear Brock comes to terms with his new reality. Meanwhile, Janice's frustration with the invasion of BopBot intensifies and Chief and Gary need to rectify a huge mistake.

As Cullen and Tolbeck prepare to give Doris' family the news that she is finito, they get a surprise visit from FBI Agent Dustin Kasprowicz. Meanwhile, Gary and Chief strategize their next move and Janice tries to convince Fatima that they may need to start looking for new jobs.

Disgraced and behind bars, former detective Josh Haldeman is interrogated by Agent Kasprowicz. Back at Dispatch, Clint and the BopBots have successfully infiltrated the department and everyone's job may be on the line. On a stakeout, Cullen is stuck with a less than enthused new partner.

Cullen is partnered with his girlfriend, Lieutenant Sophie Beyers, but as they exchange gifts to celebrate their 3 months minus 9 days anniversary, their close proximity may prove to be too much. Gary is on the run and needs to figure out what to do with Yaya. Fatima finds her voice and stands up to Janice.

Season finale. After losing yet another key witness in the Las Hormigas Cartel investigation, Cullen is forced to deal with the consequences... and FBI agent Dustin Kasprowicz. Janice returns to Dispatch to confront Clint and delivers shocking news.