The team face their toughest-ever challenge: tracking down Section Chief Lucas North, a man who has nothing left to lose.

Lucas is plunged further into his past when Vaughn takes manipulation to a new level. Ruth is followed by a council snooper.

Relations between the CIA and MI5 are stretched after an American drone is hacked in Afghanistan whilst in British care.

Beth and Dimitri go undercover when the US president visits London to chair top secret peace talks between Israel and Palestine.

When a highly skilled trio of Chinese agents arrive in London for 48 hours only, the team must find out why they are here.

Section D must welcome an FSB Officer onto the Grid to help track down a rogue nationalist from the ex-Soviet state of Azakstan.

The pressure is on for Beth when she goes undercover for MI5 for the first time, tasked with protecting a influential oil baron.

The team track a boat carrying a lethal load, fearing it is headed for the Royal Navy in Plymouth - but is this the real target?