For his debut as a film director, Hamilton creator Lin Manuel Miranda turned to some unlikely source material - an unfinished one-man show by the late Jonathan Larson.

The composer and lyricist of the groundbreaking 1990s musical Rent, Larson was a force of nature.

"He refused to write jingles for companies whose politics or ethics he didn't approve of, or to accept money for doing any sort of work for such companies.

Miranda even played Larson in a 2014 revival of Tick, Tick...

Miranda says "there are a million" moments in the film that resonate with his own life.

But the most telling comes in the second act, when Larson and his girlfriend Susan fall out over his inability to prioritise her needs above his musical ambition.

Few people realised he was capable of singing until now.

To prepare, Garfield immersed himself in Larson's life, absorbing home movies and archive recordings, and studying hand-made cards and flip-books the composer made for his friends.

"Everything was always at an 11 because of this ticking, this awareness of the shortness of life and, therefore, the attempt to create an event out of everything," he says.

"He was always singing to the back row, not just when he was singing, but when he was living.

He believes that Larson's spirit was fretting about the film - and channelling that energy through Garfield himself.

In the end, Larson didn't need to worry.

"It was an experience unlike any other, that's for sure," says Vanessa Hudgens, who plays Karessa Johnson, a key member of Larson's chorus line.

"We started rehearsals pre-pandemic and we were having the best time singing together every single day".

That's the spirit of Jonathan Larson, it's community.".

One scene, where Larson breaks into song during a party was particularly emotional because, for once, the cramped set meant they couldn't be socially distanced.

"I low-key owe my life to these guys," says the star, previously best-known for playing Storm in the X-Men Franchise.

You know, the rest of my life, I'm gonna love these people hard.".

The film they've created isn't a direct adaptation of Larson's Boho Days.

Boom!" says Miranda, who researched the "many incarnations" of the original one-man show, as well as the posthumous Broadway adaptation and Larson's archives at the Library of Congress.

Here, Miranda casts it as a duet, cutting between Karessa (Hudgens) in the rehearsal room, and Susan (Shipp), who's turned up at Larson's apartment, begging him to save their relationship.

The director says he wanted to explore the way songs can take on new meanings, even for the people who write them.

However, Miranda's love of theatre - and Larson's work in particular - imbues the film with a spirit that's almost impossible to dislike!

Robin de Jesús, who made his Broadway debut in the original production of Rent, says he hopes it will help enshrine Larson's legacy.

"Look at the show he created with Rent, and all those beautiful black and brown people that got to work there.

I know people who were in that show for years, that were able to buy homes and create stability for themselves.

"It's almost easy to think it's corny - but when you commit to Jonathan's work, it's so beautifully human and connected."