Detective Inspectors Major and Carver are the top crime-fighting duo at the Met Police's Special Investigation Unit until Major isballoonned down on the job; in an experimental artificial intelligence project, Major is brought back from the dead.

Major screws up during an investigation and Carver wonders whether to turn him in. But when he learns of the consequences, he decides to cover for him.

After he and Carver are given a new assignment by Dennett, a suspicious Major prefers to stake out Kelly's work as he has a hunch she's been seeing someone else.

The pressure is on in the latest assignment and failure could mean it's shutdown for Major once and for all...

To Carver's bewilderment, Major reveals that he is going to move back in with Kelly. Parfit discovers disturbing information in the AI Ethics files.

With Major's AI finally living up to the hype, Carver and Kelly come clean about their relationship. The team lies in wait to catch The Juggler.