James McAvoy is recalling his favourite memory from filming Dark Phoenix, the latest instalment in the X-Men franchise. They were shooting what, on screen, is a very sad scene - the funeral of a beloved character (their death is teased in the trailer, so no spoilers). However, it ended up being "weirdly hysterical".
"There was no sound because it was raining and the cameras weren't on anybody's faces - they weren't on my face anyway," explains the chatty 40-year-old Scotsman.
"So they just wanted me to look like I was saying something and we all couldn't keep a straight face. It was fine for Nick [Hoult, who plays Hank] because he's behind a lot of prosthetics, but they had to shoot it maybe 10 times and we were soaked to the skin, because we just could not stop laughing."
McAvoy, who's also known for movies such as Atonement, Split and Filth, reprises his role as Professor Charles Xavier in Dark Phoenix, which is based on the X-Men comic books (The Dark Phoenix saga, published in 1980, was written by industry legend Chris Claremont with art by John Byrne).
The story follows the much-loved superhero Jean Grey (Game Of Thrones star Sophie Turner), who, after nearly being killed during a mission to outer space, absorbs a cosmic entity and becomes the most powerful mutant of them all.
But her new, near-godlike abilities are difficult to handle once she returns home to Earth. And while 2006's X-Men: The Last Stand included elements of the Dark Phoenix story, this emotional, action-packed sci-fi thriller looks more at the psychological battle Jean faces.
Eventually, her actions tear the X-Men apart, with the heroes forced to accept that their most dangerous enemy yet is one of their own.
Michael Fassbender (42), who plays Erik Lehnsherr (mutant name Magneto), agrees it definitely feels like an extra dark chapter in the franchise.
"I mean darkness always is an element of these books I think - I guess that's the battle between Charles and Erik," suggests the Irish-German actor, whose other famous film roles include Shame, Hunger and Macbeth.
"But, yeah, for sure this is an interesting take because it's happening to a person where they're battling the dark and light within themselves and it's almost like a breakdown.
"So again, within this world of supernatural, there's a very human theme at the centre of it, which has always made this saga very real and interesting."
McAvoy, who used to be married to his Shameless co-star Anne-Marie Duff, starred as Charles in three earlier X-Men films.
But in Dark Phoenix he is able to explore new elements of his character; we will see how the founder of the X-Men "starts to believe his own hype".
"He's on the cover of Time magazine," he elaborates. "He's the public face of the X-Men - he's congratulated for all their work.
"He's the guy on the red carpets, shaking hands with presidents. He is very much like a father who loves his children and believes that they are capable of anything.
"That all sounds positive, but the downside of it is that, if they don't achieve everything, if they fall short of the very lofty expectations the world and Charles has put on his team, he feels that somehow reflects badly on him."
Meanwhile, Erik plays a pivotal role in the plot because Jean turns to him to find out how to manage her newly acquired powers, after tragic events prove that she is unable to contain the forces inside her.
As well as the gritty, raw and intense tone of Dark Phoenix, another thing that's different is that this is the first X-Men outing on the silver screen to have a female lead.
Not only is there a female protagonist, but there's also a female antagonist - Jessica Chastain plays Smith, a villainous new presence who encourages Jean to abandon her humanity and give in to her darkest urges.
And there are many empowering lines in the film, such as Raven (played by Jennifer Lawrence) saying: "We are always saving the men around here. You might want to think about changing the name to X-Women."
Do Fassbender and McAvoy feel as though the feminist script is a sign of the times, that there is now more equality in Hollywood?
"I don't know if it felt like a feminist script..." ponders McAvoy, "but it certainly felt like we were in a film that was responding to a time where feminism is having a positive impact.
"I think that Dark Phoenix - the story, the journey, the things that happen to her - might be able to happen to a fella as well."
The fact that the studio and writer-director Simon Kinberg wanted to do this and felt the market was ready for this dynamic in the cast "is a brilliant sign", he continues.
"I was pleased to be a part of that, and support Sophie and Simon in that."
"I guess the worrying thing is it is like these meetings going, 'Are the public ready for a female lead?'" quips Fassbender, to which McAvoy exclaims, "I know, right?!"
"They've always been ready," Fassbender, who's married to Tomb Raider actress Alicia Vikander, continues emphatically. "And the fact of the matter is it's like Jean Grey is the most powerful mutant.
"So it's crazy to think that she wouldn't have a film that would focus on her and she'd be the main central point."
McAvoy then points out it's "nuts" to think that even in the Marvel superhero film series they've only had one female led-film - Captain Marvel (Black Widow is on its way too).
"So, yeah, it's good that things are changing. That representation just needs to carry on, doesn't it?"