DCI Sam Tyler, in pursuit of a serial killer, is knocked unconscious by a car and wakes up in 1973, where he is a newly-transferred detective inspector working at the same station. Initially refusing to accept his situation, he finds it difficult to adjust to the attitudes and technology of the day. Investigating a murder in 1973, he recognizes a possible connection to events in the present day.
When Sam discovers that DCI Hunt plans to plant evidence to secure the conviction of an armed robber, he decides to release him.
Sam is called to a murder at a textile mill, the site of his bachelor flat in 2006. DCI Hunt suspects an outspoken union rep, but Sam tries to use his knowledge of forensic science to find the killer.
Sam arrests the henchman of Stephen Warren, a local Mr Big, when he learns the whole of CID are on his payroll. Sam also visits his childhood home to interact with his mother (using name of "Bolan", a reference to the glam rock star Marc Bolan), who was being threatened by the landlord, one of Warren's men. Sam tries to help her by giving her some money and she mis-understands his gesture. When Sam tries to go all out after Warren, he finds himself in fix when Warren sets him up in a honey trap. The girl involved in the honey trap sees the error of her ways only to be murdered by Warren. Gene disagrees with Ray who says that if they don't play the game people get hurt and helps Sam bring down Warren finally putting his guilty conscience to rest. Sam also attempts to persuade Gene to swap his Red Rum for Tyler's Proud Percy in the Grand National sweepstakes.
A football fan is killed, and Sam fears further violence in the run up to an important local derby. He and DCI Hunt mount an undercover operation in a pub to catch the suspects. Sam realises that the match is the last one he attended with his father.
Sam, convinced that his life-support system is about to be switched off in his own time, convinces himself that resolving a hostage situation will allow him to wake up.
A young man being held for a minor drugs offence dies in custody at the station while Gene and Sam are out. While Gene tries to protect his team, Sam struggles to conduct a proper investigation into the death. After alienating all his colleagues, he is able to determine that one of them forced him to take cocaine, causing a heart attack, and that the others had been covering.
Sam encounters his parents again in 1973; he believes that if he keeps his father from running away he will be awoken from his apparent coma. The closer he gets to apprehending his father, the more he hears sounds that tell him he's close to waking up. However, rather than traumatizing his family more by arresting his father, he instead lets him run away. Flashbacks throughout the entire series are revealed to have been from young Sam's memories of this incident.
A documentary about the second series of Life on Mars (2006).
Tyler has visions of someone disrupting his life support system in 2006, and encounters who he thinks is the same assailant in 1973, running a gambling syndicate and protection racket. Recognising the man as a killer he failed to stop in the future, Tyler is prepared to go to any lengths to make sure his life is not threatened and the man doesn't kill his original victim.
On an assignment to return a career safe breaker from prison for further questioning, Tyler, Ray and Chris are attacked by robbers and the man who they were taken in for questioning is broken out. Is a local gangster to blame, or is there more going on than meets the eye... specifically, was the crime actually arranged by Gene's old mentor? Meanwhile, Sam tries to break in the first black detective in the department, a man who will later become Sam's mentor when he first joins the police force.
The team receive a bomb warning, claiming the IRA has planted a car bomb in Manchester. Being from 2006, Sam realises the bomb warning reported doesn't fit with his understanding of IRA methods. However, when Sam's modern know-how fails and nearly kills Ray, the rest of the department shun his line of investigation to focus on an Irish socialist group. At the same time, Sam's visions of the future suggest that he may have suffered brain damage, affecting his higher reasoning, from having been in a coma for so long.
The body of a young woman is found in wasteland. The investigation takes the team to suburbia, where a local car dealer is throwing private parties, employing make-up girls from a local company to “help out” when the wife-swapping begins. Posing as married couple Tony and Cherie Blair, Sam and Annie infiltrate one of the parties, only to discover that it isn't as simple as they think.
The team investigates the abduction of a young woman and her daughter, who are being held prisoner by somebody who wishes the team to release a prisoner arrested on a murder charge a year ago. At the same time, Sam faces a life or death situation in 2006 when he thinks he has accidentally been given an overdose. As the deadline draws closer, Sam collapses into a deeper coma, leaving his colleagues to tackle the mystery on their own (Albeit using some of his earlier suggestions).
As heroin hits the streets of Manchester for the first time, CID and DCI Hunt want culprits for the smuggling, the dealing and ensuing violence, which becomes difficult when Annie is kidnapped by the smugglers. As Sam tries to get to the source of the influx of this deadly drug, he finds himself intractably drawn to a beautiful young woman who was witness to a heroin-related shooting... and who, he later realises, is the mother of his girlfriend in the future. At the same time, Sam's 'visions' reveal that his girlfriend has decided to stop visiting him in hospital, as she can't keep waiting for him to wake up.
A water-tight court case fails to put away a local gangster. Unable to cope with a guilty man walking free, DCI Hunt turns to alcohol but soon finds himself in a spot of bother. When it appears as though Hunt may have killed someone, it's up to Sam, torn between Gene and his replacement, a DCI who actually uses Sam's modern police techniques and vocabulary, to help him out.
Sam learns that an operation is to be conducted on him in 2006 to try and revive him from his coma. However, he believes that to return to the twenty-first century, he has to betray his colleagues in 1973 - but can he regard them as real or imagined?
A documentary about the conclusion of Life on Mars (2006).
