Follow a dysfunctional team of MI5 agents—and their obnoxious boss, the notorious Jackson Lamb—as they navigate the espionage world's smoke and mirrors to defend England from sinister forces.

Gary Sparrow is an ordinary bloke in 1990s Britain, married to the ambitious Yvonne and working as a TV repairman. Then his whole world changes when he stumbles upon a portal to WWII-era London and begins a dual life as an accidental time traveler.

Follow the defection of notorious British intelligence officer and KGB double agent, Kim Philby, through the lens of his complex relationship with MI6 colleague and close friend, Nicholas Elliott.

During the Suez Crisis of 1956, two young clerks at the stuffy Foreign Office in Whitehall display little interest in the decline of the British Empire. To their eyes, it can hardly compete with girls, rock music, and the intrigue of romantic entanglements.

After the sudden death of ex-Secret Intelligence Service man Alexander, his wife Alison investigates when mysteries from her husband's past come knocking.