Major, Carver and Kelly have gone their separate ways. Things are looking up for the AI-enhanced Major, whilst Carver is gunning for a promotion and is knee deep in a new case.

After visiting an informant in prison, Major and Carver re-examine an infamous cold case which opens old wounds for Major. Carver sees Major's malfunctioning is getting worse and turns to Dr. Parfit for help.

Taken off the Chelsea Bridge case, Major and Carver are assigned an investigation into reports of a dangerous new drug used in an underground MMA fight ring.

Instead of fixing Major, Dr. Parfit creates a replacement A.I. for SIU. Kelly thinks she's found a lead in the Chelsea Bridge case but Carver hasn't got time for her theories now Major's place in the department is seriously threatened.

Carver rescues a dangerously unstable Major from the brink. Dennett calls in a favour from Millikan Biotech, but her attempt to save Major backfires, leaving an unsuspecting Major still in mortal danger and Carver wracked with guilt.

With just three hours left to live, Carver and Kelly find a collapsed Major and try to get him to accept the truth. But Major is determined to solve Chelsea Bridge and exonerate his dad before his A.I. shuts down and he dies.