To adapt David Mitchell's Cloud Atlas, directors Tom Tykwer, Lana and Andy Wachowski realized they had to break apart the centuries-spanning novel's six connected tales and refashion it anew.

"We all felt that the book affects your brain," Lana Wachowski told reporters at the Toronto International Film Festival on Sunday, the day after the film's festival premiere.

"Your brain no longer sees six stories, but it starts making connections…We wanted to make a movie about [that], what's happening in your brain."

The resulting ambitious, fast-paced, cinematic adaptation required a cast willing to portray a multitude of characters of different genders, ages and ethnicity. The film's ensemble cast (stacked with Oscar-winners, acclaimed veterans and up-and-comers) were willing and eager to go along, putting their faith in the trio of directors, whose past credits include Run Lola Run and The Matrix films.

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Oscar-winner Tom Hanks described Cloud Atlas as the 'perfect blending of the literature of David Mitchell and the cinematic power of these three [directors].' (Aaron Vincent Elkaim/Canadian Press)

"They've talked about this for so long that the vision is clear. There's a safety, a safe feeling that came with that. I would have tried anything they said," Halle Berry admitted.

"While it was big and overwhelming and daunting to them, they never let it trickle down to us. I think we all had a good acting experience, where we all got to play."

While cast member Hugh Grant — who received a birthday serenade from the gathered press and his Cloud Atlas co-stars — quipped that he took on the project to show he had  "more strings to his bow," all the actors seemed to have enjoyed the challenge, which often included undergoing major prosthetics that sometimes left them unrecognizable.

When asked, each quickly offered up a favourite character he or she portrayed, from Tom Hanks as a cockney gangster-turned-author, Grant's menacing turn as a bloodthirsty cannibal warrior, Hugo Weaving as a demonic vision and Susan Sarandon's delight at playing a man.

"It is fantastic source material," Weaving noted, adding that each cast member realized "we were all going to have to take a kind of jump off a cliff into what this film was going to be…[That] leap of faith was something that galvanized everyone. It actually made it fun. It felt like doing something that was risky and different.

'It's kind of like a hug that keeps getting tighter and tighter… the connection becomes evident'—Tom Hanks

"There was always that sense of nervous excitement about going into the next day, the next character."

While in Mitchell's novel the six tales are nested into one another, Tykwer and the Wachowskis immediately thrust the audience into the different stories and jumps between each tale.

Hanks admitted that the actors were initially scratching their heads at the first read-through of the script.

"Much like the film itself, the initial seven pages or so of the screenplay raised questions, as in 'Who are these people and what's going on?' But it's kind of like a hug that keeps getting tighter and tighter… the connection becomes evident," he said.

"By the time I was reading the last 40 or 50 pages of the screenplay, I was completely involved in each of the individual struggles and understood that these were characters that were having to make the choice between cruelty and kindness, and that decision was going to change the world from that point in.

"It's the perfect blending of the literature of David Mitchell and the cinematic power of these three [directors]

," Hanks continued.

"It's not six different movies. It's not even two different movies. It is one example of cinematic literature that examines the connectedness of the human race through all of time."

TIFF continues through Sept. 16.