The Simpsons brand new season will premiere with the show’s first ever all-musical episode, which is set to include a number of famous voices.

Kristen Bell, who voices Princess Anna in Frozen, will feature as Marge’s singing voice alongside Brian Cox, Fargo star Cristin Milioti and Timothy Olyphant - who also starred in 'The Star of the Backstage' episode.

The details for episode 1 of season 33 were first revealed at Comic-Con during the weekend. Executive producer Matt Selman said that it will be “the most musical episode we've ever done,” when speaking to Entertainment Weekly.

“Almost wall-to-wall music. It's like a Broadway musical of an episode with all original songs,” he added.

The plot for the forthcoming Simpsons episode was also revealed. “Marge has amazing memories of being the stage manager of her high school musical, Y2K: The Millennium Bug, and decides to restage it with everyone 20 years later for one last show.

“But when her old high school nemesis comes to town, she realises that her high school memories aren't what she thought they were.”

Selman also spoke about Kristen Bell taking on the role for the episode. “We all love Marge's voice [Julie Kavner] but this is the singing voice that's different, let's just say.

“The only place Marge sang beautifully was in her head, so she has a magical inside singing voice that only we can hear. When she sings, it comes out beautiful, like Kristen Bell.”

It was also revealed that this year’s Treehouse Of Horror special will feature five segments instead of the usual three.

This season will also feature a two-part episode titled 'A Serious Flanders'. The episode is described as an “epic love letter to the show Fargo, prestige crime dramas, and the world of streaming television.”