Every year in Britain, more than 600 people commit murder. The majority of these killers will eventually be sent to Gartree Prison in Leicestershire.

This Cutting Edge documentary, filmed over six months at HMP Gartree - home to Europe's largest population of life-sentenced prisoners - provides an unprecedented insight into the lives of convicted killers facing a lifetime behind bars.

These men will die in prison unless they can convince the authorities they have changed and are no longer a risk to society.

With unique access to Gartree's cells, landings, segregation unit and visiting rooms, Lifers explores the everyday realities of prison life for those convicted of murder.

The documentary examines the psychological impact of killing, following prisoners as they try to come to terms with what they've done, with varying degrees of remorse and contrition.

Unlike regular prisoners, lifers do not have a fixed release date; after serving a minimum term behind bars (set by the trial judge), they will only be set free if they can prove that they are no longer a danger to the public.

Lifers explores the behavioural courses and psychological interventions that convicted killers are expected to undergo as part of their rehabilitation.

The film follows this process through to the parole board, where a team of independent experts must decide whether a prisoner is safe to be released back into the public or must remain behind bars.