SUNSET Boulevard is dark. It's a study of obsession, delusion, loss, failure and ageing. As Danny Mac points out, it's not your average "flashy jazz hands" musical.

And, although it's set in post-war Hollywood, its themes of exploitation and manipulation are relevant in today's film industry. Based on Billy Wilder's Oscar-winning movie, Sunset Boulevard is the story of Norma Desmond, a faded silent screen goddess living in the past in a Los Angeles mansion. When young screenwriter Joe Gillis, on the run from debt collectors, crosses her path, he's seduced by the ageing film star and her lavish lifestyle. Norma sees in Joe an opportunity for her big screen comeback, and so begins a tragic romance.

Danny plays Joe in Andrew Lloyd Webber's Tony-winning production, opposite Ria Jones who earned rave reviews standing in for Glen Close as Norma for some performances in the West End.

"Of all the jobs I've done, this is the one I'm most proud of," says Danny, who has a WhatsOnStage nomination for Best Actor In A Musical for his role. "Right from rehearsals, we felt it was something special. It's not a mainstream musical - it's not Hairspray or Dirty Dancing where the audience leaves in a feelgood glow. It's a classic, it's quite chilling, its score gives you goosebumps, and you walk away talking about its themes and characters.

"It feels strangely contemporary. I spent a lot of time in LA and had those conversations with film people. I get it."

Reflecting on Joe and Norma's complex relationship, Danny says: "They manipulate each other. He enjoys her wealth and thinks she can get his career going. She wants him to write her a screenplay which, in her fantasy world, she thinks will get her film career back on track. Joe is the narrator, we see events through his eyes, and he tries to justify what he does. He's selfish and driven, but he'd argue that you need to be in that industry. He's flawed - as Norma is. I don't need to make him likeable, I need to make him believable."

Does Joe care for Norma, despite using her? "He becomes fond of her, they have a relationship" says Danny. "But Norma is vulnerable. She's spent her life in the industry and, like many stars who started out as children, she's had everything done for her. People like that can barely tie their own shoelaces. She feels she's nothing without the spotlight. There's a fine line between having attention and what you have the attention for.

"She was from the era of silent movie stars who were huge, then cast aside when talkies came in."

The show's powerful score includes With One Look, As If We Never Said Goodbye and The Perfect Year. "People know the songs, but not necessarily where they came from," says Danny. "The score was what made me do this show. I wasn't familiar with the story, but when I played the soundtrack I knew I had to do it.

"Having now watched the movie, I see how the music in the show drives the action. It was the first film made about Hollywood. Norma was the first of the generation of actors who became washed up."

Norma's delusion is aided by her faithful butler and chauffeur Max, a former film director who has stood by her. "One of my favourite moments is when Joe and Max are together on stage. Max is protecting Norma, Joe is using her. In their own way they both create the illusion she craves," says Danny.

Danny grew up on the south coast and got into theatre at an early age, playing Gavroche in Cameron Mackintosh's tour of Les Miserables, later reprising the role in the West End. He went on to appear in shows such as Wicked, Legally Blonde and On the Town. He played Mark "Dodger" Savage in Channel 4 soap Hollyoaks from 2011 to 2015 and will soon be seen in popular supermarket sitcom Trollied. Danny was a hot favourite on Strictly Come Dancing in 2016, reaching the final.

Does he show off some moves in Sunset? "There is a dance, but it's a pivotal scene and certainly wasn't included because of me and Strictly," he smiles. "It's the first physical contact between Joe and Norma, it's very tender."

Danny is heartened by the response of younger audiences to Sunset, and hopes it will encourage them to see more theatre.

"My 12-year-old nephew said it was the best thing he'd ever seen. I think theatre should as accessible as Netflicks," says Danny. "I was a smalltown boy who fell in love with theatre. I wouldn't be where I am without musicals."

* Sunset Boulevard runs at the Alhambra from February 5-10. Call (01274) 432000.