"This is different from other superhero films," says Will Smith, star of the forthcoming film adaptation of DC Comics' Suicide Squad. "It's not about good versus evil. It's about bad versus evil."
Suicide Squad, starring Smith, Jared Leto, Margot Robbie, Viola Davis and Cara Delevingne, and directed by David Ayer has been given the tagline "Worst Heroes Ever".
The film title refers to its protagonists being a bunch of ne'er do-well superheroes who are offered a chance to redeem themselves on a mission expected to end in certain death.
Smith believes the film "is an exploration of the concept of redemption".
"We all discussed it as a cast in rehearsals - where is the line between bad and evil?" he says.
"You might do bad things for good reasons, or maybe even for fun. We decided that if you are bad, you are always redeemable. It's evil that isn't."
David Ayer, the American-born director of films including Fury with Brad Pitt, and End of Watch with Jake Gyllenhaal and Michael Pena, says he has been a fan of comic books since he was a child.
"It was the chance to recreate a film that looked like a comic book that really made me want to direct this," says Ayer.
"While every kid loves your Batman and your Superman, you can identify with the villains a bit more as you grow up, because they are a little more morally complex. So my challenge was how to make an audience fall in love with a whole cast of them."
Smith's character of Deadshot is the leader of the group, which also includes Jared Leto as the Joker - previously portrayed by the late Heath Ledger in the Dark Knight series.
Smith says "Deadshot is the leader, the emotional heart of the Squad - but all of them suffer from low self-esteem, otherwise they wouldn't have created these lives for themselves".
"There's one part where Deadshot yearns for the life he could have had in the military, he has this what-if moment where he sees the path he could have taken very clearly. So audiences can see the choices that often make for a bad man or woman, what has driven them there.
"Viewers should be rooting for them, when it becomes clear their mission is destined to fail, to make a right choice, to work together as a group."
Australian actress Margot Robbie, most recently seen this summer in a new adaptation of Tarzan, signed up to the Squad, she recalls "when there was no script and no one else attached apart from David".
She continues: "Something in my gut said, 'Yes, this is the one you should do' even though I had another project lined up."
She plays Harley Quinn, the white-haired, baseball-bat-wielding cheerleader who was once a psychiatrist. Along with Cara Delevingne as the Enchantress, Karen Fukuhara as Katana and Viola Davis as Amanda Waller, the tough commander who authorises the mission, the male to female ratio in the squad is more equal than in other superhero films, as Delevingne points out.
"I always remember seeing the kind of comic book movies where women are the love interest or just a sidekick.
"Of course, there are still more male characters but all the women are on a par with them, and they have the best lines.
"Especially with Wonder Woman coming out next year, it's important to find and tell women's stories in this superhero world, because the films are just so popular with audiences."
While DC Comics' earlier 2016 predecessor, Batman v Superman: Dawn of Justice, was a critical - although not a commercial - flop, there are expectations in Hollywood that Suicide Squad could break August box office records.
Both Ben Affleck's Batman as well as another Justice League character, Flash, are confirmed to have cameos in the film, as the franchise is built up ahead of the 2017 releases of Wonder Woman and Justice League. Robbie believes she could do "10 Suicide Squad movies if they wanted me to - we are a family now".
"David Ayer got all of us together for weeks before filming started to rehearse and to thrash things out about our characters," she explains, "and so we ended up bonding off screen, we truly became a squad. We were joined at the hip," says Robbie.
"David has this really interesting rehearsal period where he digs into your life, so the whole cast shares really deep stories about ourselves," adds Will Smith. "You just think he's being a nice guy, and then in the middle of filming, he throws your greatest childhood trauma at you and adds, 'The Joker did it'. It certainly gets you working.
"He actually had to stop us being so cuddly with each other, because he would find us hanging out together in one trailer in between filming. He would say, 'You don't like each other until later on in the movie, stop it.'
"But this cast bonded in a special way that isn't always the case, we all felt honoured and excited to be a part of it, and everyone checked their egos in at the doors. We definitely like each other, and I can tell you that doesn't always happen in movies."
Suicide Squad is released in the UK on 5 August.