You would need a heart of stone not to enjoy this documentary about actor Danny Trejo, star of the cult Machete pictures, whose extraordinary life took him from a boyhood in the tough Pacioma district of Los Angeles, heroin abuse in his teens, violent crime in early adulthood and then jail time in various institutions, where his terrifying alpha-Latino image and boxing skills earned him a reputation as someone not to be messed with.

After he was released, he went to AA, got clean, and landed a job as a coach and then as an extra on a film set. He became adored by film-makers and casting directors as the real deal, a tough guy whose tattoos alone were enough to terrify. He rose from non-speaking parts (billed as Inmate #1, Gangbanger #1 etc) to speaking roles in movies such as Heat, Desperado, Con Air and family movies including Spy Kids; his gift for granite-faced black comedy in Robert Rodriguez’s Mexploitation film Machete made him a legend. He also became a friend of ex-con, pulp novelist and actor Eddie Bunker (Mr Blue in Reservoir Dogs), who probably deserves a documentary of his own.

The scenes here when Trejo returns to prison to address convicts about getting and staying clean are powerful in their candour and simplicity; he is visibly shaken by the memories this is stirring up. And Trejo has a staggering anecdote about being on the set of Muppets Most Wanted in 2014 when the news came through that his mother had died. Trejo stayed tough and impassive right up to the moment when an actor held Kermit up and in character said to him: “I’m really sorry about your mom.” At this point, Trejo broke down in tears.

This documentary is a bit reticent on the subject of racism. It’s not a subject that Trejo addresses, other than to say that cops who used to pull him over now do so to get selfies. Yet it’s an amazing true-life success story.

• Inmate #1; The Rise of Danny Trejo is available on digital platforms from 22 June.