Sam is experiencing visions and pains that suggest that his life is in danger in 2006. At the same time, he runs into the younger version Tony Crane, a twenty-first century killer who Sam helped to convict. Sam comes to believe that Crane has escaped justice in 2006 and has come to wreak revenge on his comatose nemesis by torturing him...to death.
Sam receives messages from 2006 saying that his mentor, Glen Fletcher (Ray Emmet Brown) has died. He's shocked to meet a younger version of Fletcher in 1973, especially when he finds that his mentor has not yet grown into the man who he looked up to. Meanwhile, a prisoner's escape triggers Sam's suspicions about crooked dealings within the CID.
Manchester is beset with bomb threats that Gene readily pins on the IRA, but Sam's knowledge of history makes him doubt Gene's assertion. However, messages from 2006 and a grave mistake in 1973 are giving Sam reason to question his own judgment.
A very ill Sam Tyler has reason to believe that he's been given an overdose of medication in 2006. While struggling with this, he's called into CID to assist with a troubling kidnapping case. With Sam not quite himself, it's up to the rest of the team to solve the case and save the lives of a mother and daughter.
Sam hears the voice of his girlfriend Maya (Archie Panjabi) from 2006, asking him to let her go. At the same time, an investigation of the burgeoning Manchester heroin trade leads him to meet an unexpected acquaintance from his twenty first century life.
DCI Gene Hunt finds himself on trial for murder and soon all of CID are after him. But DI Sam Tyler believes otherwise. He goes to find his innocence. Even if that means making Gene dress as a road safety squirrel.