Jim Sturgess has revealed that his new film Cloud Atlas is "crazy".
The Wachowski siblings' big-screen adaptation of David Mitchell's novel also stars Tom Hanks, Halle Berry, Hugh Grant, Ben Whishaw and James D'Arcy, each playing multiple characters in various time zones and places.
"It was epic, it was exactly that. It was epic and it was crazy, and more than anything, it was just a lot of fun," he said at the film's UK premiere in London.
"You had a lot of actors from all areas, these big Hollywood names and these younger British actors. There were people from all walks of life but it really felt like everyone was making their very first film for the first time because none of us have made a film like this before."
Jim revealed that the casting was cleverly done by directors Lana and Andy Wachowski.
"Lana and Andy had told me very specifically that they wouldn't just let me play any character just for the sake of it. There had to be some sort of connection to the other characters that you play," he said.
"I was really lucky because I felt like my main two characters were essentially telling the same story of slavery and the abolishment of slavery but in very different time frames."
The One Day star admitted that the script got a bit confusing: "You had to treat them all as individual little films. It was Tom Hanks' idea to pull out all the pages from the script and put your stories into one so you could get a clear idea of the journey your character is on."