Simon Helberg has joined the cast of new musical romance 'Annette.'

Simon Helberg

Simon Helberg

The 'Big Bang Theory' star will be joining Adam Driver and Marion Cotillard in the film, which follows a pair of star-crossed lovers in Los Angeles.

Simon will play the role of 'The Conductor' in the film, which will be directed by Leos Carax in his first English-language film.

The 38-year-old played Howard Wolowitz in 'The Big Bang Theory' and has also appeared in 'Florence Foster Jenkins.'

Oscar-nominee Driver will play a stand-up comedian and 'La Vie En Rose' star Cotillard will play a modern opera star.

The story will bring the U.S. rock band 'Sparks' together with music producer Marius de Vries, who has worked on 'La La Land', 'Moulin Rouge' and 'Cats.' The music from the film was originally intended to be a 'Sparks' album.

But Helberg himself is unlikely to watch the movie as he previously admitted he finds it "difficult" watching himself on the screen.

He said: "I do have sometimes a difficult time watching myself. This one has been an interesting journey, because it's obviously something I care so much about, because it's wonderful and the people are so wonderful. So it definitely had a lot of pressure built in just to doing it, and I have a hard time knowing where to kind of find validation and determine whether I've done my job or done it the best I can. It's easy sometimes to look outside and have people say nice things and go, 'Oh, I feel great,' but I think that's filling that cup from the wrong spout. It's a tricky balance."