The final episode reveals that the Life on Mars/Ashes to Ashes world is a form of limbo or https://en.wikipedia.org/wiki/Purgatory, for "restless dead" police officers. These restless dead include the main characters Gene, Ray, Chris and Shaz (Montserrat Lombard ), all of whom died in violent circumstances but there may be others.
The revelation of their deaths comes as a surprise to all except Gene, who knew they were all dead but who had forgotten the circumstances of his own death, due to the passage of time. All except Hunt "move on" as he takes it upon himself to act as a psychopomp or "ferryman ", to all of his officers, helping them on their way to The Railway Arms (their euphemism for https://en.wikipedia.org/wiki/Heaven, filmed on location at The Horseshoe Inn, 26 Melior Street, London).
Gene returns to his office, where a newly dead officer arrives, demanding his iPhone (implying that he is from the present) and asking where his office has gone, in a very similar manner to the arrival of Sam Tyler (John Simm ) in the first episode of Life on Mars. In fact, Gene's last words — "A word in your shell-like, pal" — are the same as his first words to Sam Tyler in the first episode of Life on Mars.
