Black Bird star Taron Egerton said he found the “incredible” true story behind the series “utterly compelling and gripping.”

The actor has transformed from starring as Elton John in Rocketman to prisoner Jimmy Keene for the new psychological thriller on Apple+ TV airing on July 8.

The six-episode series follows Egerton’s character, who is serving 10 years in a minimum security prison, enter a maximum security prison for the criminally insane with a mission to befriend a suspected serial killer in exchange for freedom.

Talking about what drew him to the role, Egerton told the PA news agency: “I felt that it was a script that was completely without sentiment or glorification.

“It was unashamedly an examination of one of the ugliest sides of human nature, particularly of masculinity.

“I thought there was something really unapologetic about the fact that it was looking at how awful men can be and also as the show unfolds, examining why that’s in us.

“On the page it was just electrifying to read from the moment you started reading it, you just want to know what happens, it’s such an exciting premise.

“When you add to that the fact that it really happened, it was not something I could pass on, it was such a great opportunity.”

Ray Liotta deathRay Liotta (Ian West/PA)

The highly-anticipated series, written by Dennis Lehane, is based on a true story and will feature late Goodfellas star Ray Liotta in his final TV appearance, playing Egerton’s on-screen father.

Egerton added: “I think it’s important to make a distinction between the real guy and the character I play.

“I suspect that Dennis did some work in terms of taking licence with who the character is on the page, but the real Jimmy Keene is in our show, he cameos and he’s a producer.

“I certainly get the impression that while he did stray from the path and was involved in some dodgy dealings, I don’t know that he was quite as much of a narcissistic, misogynistic man.”

The 32-year-old actor added that he couldn’t believe a prisoner had been offered the chance to have their “sentence wiped” in real life.

“It just wouldn’t happen in Britain, would it. It’s a kind of wild thing. It’s just an incredible true story and I found the whole thing utterly compelling and gripping,” he said.