Set in the near future, Code 404 revolve around two Detective Inspectors, DI John Major and DI Roy Carver, who are the top crime fighting duo in the Unit. But when an undercover sting goes horribly wrong, Major is gunned down on the job and killed. How will the SIU function without Major? It doesn't have to. As an ‘asset' considered too valuable to lose, Major's body is fast-tracked into an experimental Artifical Intelligence project to bring him back from the dead. The only problem is, Major 2.0 may look like and sound like the original, but something has been lost in translation - quite a lot actually. His arrogant demeanour and gung-ho approach remain but his crimefighting instincts have completely deserted him. Somehow, Major's error-strewn hunches and Carver's scrambling to make good allows them to just about scrape by. But while the experiment might be hailed as a success, on the front line Roy Carver is left dealing with an increasingly deluded partner.
On limited duties pending an investigation into their last case, Detective Inspectors Major and Carver find themselves at an all-time low. So, when one of their own within SIU is murdered, Major and Carver become hellbent on solving the case and proving their worth. But it’s bigger than they thought... They discover they’re dealing with a twisted serial killer whose sights are now set on them. With lives at stake, they need to work together, but tensions run high and fractures in their partnership begin to worsen. Can they hunt them down before it’s too late?
Having cracked The Juggler case with his long-suffering partner, the resurrected DI Major has finally reached his potential as the top cop in the SIU. But it came at a price. At last realising that his best friend had shacked up with his wife Kelly while he was “away” (and a bit before), their partnership is over, and the pair go their own ways. But when a 20-year old cold case is reopened, the pair find themselves back together and thrown into the action. With an impending divorce, the return of his long-time absentee dad, and danger around every corner, the pressure seems to be getting to Major and he starts exhibiting strange behavioural glitches. However, much to Carver’s concern, the problems are more serious than a typical reboot can solve, and our cyborg hero may be looking at terminal failure.
John Major had it all: wife, best friend, glittering career in the police force... when his cover was blown and he met an untimely death. One year later, he's back - part AI and better than ever... or so he'd like to believe. Full of glitches, he's got to track down the person who shot him, prove himself as a cop so as not to get shut down, save his marriage and his friendship with his partner to boot.