Scott and Stonebridge head to Colombia in search of Leo Kamali, the apparent financier behind a Mideast terrorist group run by the elusive al-Zuhari, but the operation gets complicated when an agent with whom Scott has history shows up under an alias.

After a relentless assault from Miguel Gomez, S-20 orchestrates a brazen heist in order to locate the elusive Kamali. In Beirut, a close encounter with a group of assassins leads Dalton to Sebastian Gray, a onetime MI6 operative who's privy to al-Zuhari's dark plans.

Kamali wins Scott & Stonebridge's trust by leading them to an ex-SAS mercenary who's planning to smuggle al-Zuhari into Beirut. Russian mob boss Arkady Ulyanov vows revenge on the men who killed his son in Colombia & enlists an irresistible siren to locate one of them.

Stonebridge, Scott, Richmond & Martinez stage a daring rescue mission after Leatherby takes Kamali's daughter Ester hostage. Meanwhile, Kamali and Dalton allow Sofia to escape, hoping she'll lead them to al-Zuhari. Instead, they encounter a dangerous and surprising foe.

Section 20 sets up shop in Budapest, where the apprehension of an ex-IRA gunrunner leads to a shocking discovery: a planned al-Zuhari attack on an upcoming holy day. Fighting the clock, the team looks to thwart a weapons heist orchestrated by MacKenna at a railway yard.

Scott and Stonebridge follow their last lead in an effort to track down MacKenna and the weapons intended for an imminent al-Zuhari strike. In an explosive climax, Section 20 finds itself under siege, with top-secret NATO data in danger of falling into terrorist hands.

Posing as drug runners, Scott and Stonebridge imbed themselves in a Russian prison in order to prevent Erik Andersson, an expert computer hacker facing extradition to the U.S., from breaching the firewalls to the NATO hard drive seized by MacKenna.

Scott looks for an escape from Black Bear Prison, while Locke becomes suspicious of Kamali. The team races to locate Stonebridge, whose condition grows more dire when he encounters Al-Zuhari's plan firsthand. Continuing his vendetta, Ulyanov closes in on the two agents.

Scott and Stonebridge aim to keep their promise to protect Ester. After questioning a suspect from the raid on the facility, Richmond and Martinez follow an Al-Zuhari associate, gaining key intel. Believing an attack is imminent, the team set out to stop an infiltrator.

Scott and Stonebridge come face-to-face with a new key player in Al-Zuhari's plan. As the timetable for the attack accelerates, the team resorts to questionable measures, sparking conflict within the unit.