In the series finale, Alex's quest to learn the truth about Sam Tyler's death leads her to ignore the team's investigation of a diamond heist. When Gene catches wind of what she's up to, he heads after her, leaving Ray, Chris and Shaz on their own for a sting operation.
In the Season 3 premiere, Alex wakes in 1983 to find herself in a hospital bed, where she's been since being shot by Gene, who is now on the run. She's soon haunted by the ghost of a young policeman. CID, meanwhile, investigates the case of an abducted girl.
Gene is determined to take over an undercover operation on his turf that's being run out of the Hanfield police station. Alex, meanwhile, believes the police officer haunting her may be her key to returning home.