A Section 20 operation in the Bakka Valley goes badly resulting in Baxter's death. Stonebridge and Scott are enjoying a well-deserved vacation. Recalled to duty, they team up with Kim Martinez to track and capture the killer in Colombia.
Section 20 tracks facilitator James Leatherby in Beirut. They continue to use Kamali in operations on al-Zuhari and Leatherby. Dalton is making bad decision due to her emotions over Baxter's death. Section 20 acts on tips about al-Zuhari.
Leatherby takes Kamali's daughter, Ester, hostage. Section 20 attempts a brazen rescue mission to get her back. Dalton tortures and interrogates Sofia for information. The escape ruse that Kamali and Dalton use has surprising consequences.
The tracking of McKenna leads Section 20 to Budapest; At Dalton's funeral, Richmond learns that she has a son. Twenty acquires an optic drive with a message from al-Zuhari about an attack. It seems the IRA and Al-Zuhari have joined forces.
Decoding the NATO hard drive would breach all NATO security. Scott and Stonebridge go undercover in a Russian prison to prevent a hacker from breaching the firewalls of the hard drive. Stonebridge continues to struggle with his focus.
Though weaker, Stonebridge gets direct knowledge of Al-Zuhari's plan. Still imprisoned at Black Bear, Scott looks for an escape. Suspicions about Kamali continue to mount. Ulyanov's vendetta against Scott and Stonebridge intensifies.
With the death of Leo, Ester needs protection. Scott and Stonebridge keep their promise. Richmond and Martinez follow up on intelligence gained from facility workers. Section 20 attempts to stop a train before it reaches a populated area.
Kamali is alive. He fooled everyone when he faked his death. Locke makes a deal with Ulyanov to capture Kamali. Kamali's team attempts to deploy the weapon at Ramstein AFB. Stonebridge and Scott have many important decisions to make.