MI-5

An Al Qaeda cell kidnap a soldier and demand that Remembrance Sunday be cancelled.

Harry vows revenge by taking down the head of Russia's intelligence service.

Lucas reveals that the Russians interrogated him about MI5's most secret spy operation.

Al Qaeda's number three wants to negotiate, and Lucas's double agent status is tested.

Ros goes undercover in the City to flush out a dangerous international financier.

A teenage boy stumbles upon a government conspiracy and is absorbed into the world of MI5.

Harry is imprisoned and accused by MI5 of being the Russian mole.

The team must turn to a traitor amongst them when the Russians launch a nuclear strike.