Tyler, being a 21st-century detective, is forensically aware and procedurally correct, whereas Hunt values violence, corruption and gut instinct in order to catch criminals.

While in 1973, Tyler often sees images from the present day on his television, hears loved ones and medical staff talk about him and to him through phones and portable radios, along with being stalked by Test Card Girl (Rafaella Hutchinson and Harriet Rogers) and experiencing recurring hallucinations.

While in 1973, Tyler finds himself investigating many crimes with the CID team from serial killers, armed robberies, murders, a hostage situation and a suspicious death in police custody.

During the series finale, a new character is introduced: Acting DCI Frank Morgan (Ralph Brown) to temporarily oversee CID after Gene Hunt is wrongly suspected of murder.

He also reveals that "Williams" was sent undercover with a fake identity, DI Sam Tyler, to infiltrate Hunt's team, but developed severe concussion and amnesia after a bad car accident on the way.

Morgan convinces Tyler that exposing Gene Hunt and his CID team while on an undercover operation to catch a violent armed robber, Leslie Johns (Sean Gilder), will enable him to return to the future.

While the undercover operation is in progress on the train that Leslie Johns and his team is attempting to rob, Chris, Gene, Ray and Annie all come under fire and are caught out in the open.

After alienating his cold, unsympathetic colleagues and confiding to his elderly mother, he commits suicide by joyfully taking a running jump off the police station roof.

After being thanked by the team and kissing Annie, Tyler receives a message on Gene's car radio from 2007 that he is "slipping away", implying that he has chosen to stay in 1973.

Tyler later married Annie Cartwright and died in 1980 after unintentionally driving his car into a river while in pursuit of a suspect, from which his body was never recovered.

In the fifth episode, Gene destroys Tyler's clothes (which Alex had requested from Manchester) and the censored file in order to prevent her from learning the truth about his death.

In the finale, it is revealed that some years later, Sam Tyler had taken Gene's offer of going "to the pub"—accepting his death in the real world, and moving on from his life in the past.

Tyler is displayed to be a professional and procedurally correct officer who dislikes corruption and brutality, with a strong moral centre and sense of justice.

For the majority of his time in 1973, Tyler wears a black leather jacket with jeans or plain trousers and typical shoes of the day, with his collar spread out and no tie, unlike the rest of Hunt's CID.

Carling acknowledged Tyler's bravery in saving his colleagues during the last episode of Life on Mars, but he still criticises his tendency to disobey Hunt.