The sequence is filled with the kind of exposition-heavy dialogue (“Cross has the place loaded with transmission blockers!”) that starts to sound like gibberish upon repetition. The problem? There is a lot of repetition as director Peyton Reed (The Break-Up) requests take after take, either to resolve technical glitches, to alter dialogue, or because an actor flubs a line. (At one point, ­Douglas refers to “Howard Stern,” the father of shock radio, when he’s meant to say “Howard Stark,” the father of Iron Man Tony.) By the time Douglas raises his F-bomb query, even if he’s (kind of) kidding, it’s fair to say he’s speaking for everyone on set.

Of course, it’s a minor miracle there even is a set. British filmmaker Edgar Wright (Shaun of the Dead) spent years developing Ant-Man for the screen, but last May, two months before production was scheduled to begin, he suddenly split and took an instant vow of media silence. (In a vague joint statement with Marvel, he blamed “differences in their visions of the film.”) His exit prompted a nerve-fraying search for a new director and a flurry of questions: What really happened? Would the film still make its July 2015 release date? Without Wright, would the stars bail? And then there’s the biggest question of all: Why the hell would anyone make a movie about Ant-Man anyway?

The history of this film is almost as serpentine as the history of the char­acter. Way back in 2001, Wright and fellow Brit Joe Cornish (Attack the Block) wrote an Ant-Man treatment in the spirit of Elmore Leonard that revolved around Lang’s criminal activities. In 2004, they successfully pitched it to Kevin Feige, who was then running production at Marvel Studios. (He’s now president of the whole company.) At the time, Marvel was far from the movie powerhouse it is today. That began to change in 2006 when the studio announced an ambitious production slate—one that included Iron Man, Thor, and Captain America—and Ant-Man was pushed to the back burner for seven years. But Wright said he was grateful the development process took so long. “I’d rather do the film with 2015 effects than with 2005 effects,” he told EW in August 2013.

A few months later, in December 2013, Marvel announced that Rudd, a longtime friend of Wright’s, had been cast in the lead role. Just as Ant-Man might seem a strange candidate to become a big-screen superhero, the Anchorman and Role Models star seemed an odd choice to play one. But Feige insists Rudd was perfect for a hero with an unheroic history. “We wanted Scott Lang to have made mistakes that cost him dearly,” he says. “But we wanted the audience to be rooting for him despite that. Paul Rudd can do almost anything and you’re still charmed by him.”

The movie, meanwhile, couldn’t seem to catch a break. On May 23, 2014, Marvel and Wright broke the news that the director had left the project. Wright had reportedly jumped ship after Marvel presented him with a new script that had been rewritten without his input. “It is true that there were disagreements about the direction the script should take,” Feige says now. But “everything was aboveboard. Everything was done with everybody else’s knowledge. There was a sense of ‘We’re going in this direction, you’re staying in this direction—maybe it’s best that we end as friends.’”

The news of Wright’s departure came as a huge blow to Rudd. “It all happened very quickly,” says the actor, months later on the Ant-Man set. “I was devastated.” Lilly assumed the movie was dead. “Then I found out, ‘No—we’re moving along,’” she says. One small problem: Lilly had not yet signed her contract, she says, which meant she could walk out too if she wished. No one wanted that, but she refused to put her Jane Hancock on the dotted line until she saw the new Marvel-revised script. The studio kept her waiting. “I got held off for months,” she says. “Marvel knew [that first revised screenplay] wasn’t good. They just knew it was in the direction they wanted.”

Rudd himself worked on the script with Anchorman director Adam McKay, who also briefly flirted with directing Ant-Man. (He ultimately passed.) The clock was ticking. If the film was still going to meet its July 17, 2015, release date, Marvel had to find a replacement, fast. The ­studio’s collective blood pressure finally dropped after they met with Reed, who had devoured Marvel comics as a child and has known ­studio president Feige for more than a decade. Marvel then recruited rising screenwriting team Gabriel ­Ferrari and Andrew Barrer to rewrite (and rewrite) until everyone was satisfied.

Despite all that script drama, Rudd says he still sees the ­narrative blueprint Wright and Cornish created. “The bones of it is really Edgar and Joe,” he says. “It’s been an emotional roller coaster, but I’m very excited now.”

That lean, mean physique isn’t just for show. When we first meet Lang, he is in prison for stealing from the CEO of a company that was itself stealing from its employees. “There’s a prison fight and you’ve got to buy Paul in that role,” says Reed. Lang longs to go straight—he has a young daughter he wants to build a relationship with—but when he leaves the big house, he ends up nabbing Pym’s Ant-Man suit. Was he set up? “There might be stuff going on that Scott doesn’t know about that’s a lot bigger than him,” Reed says.

Having proven his light-­fingered bona fides, Lang is trained by Pym, who plans to use him to thwart Darren Cross (Stoll). Cross is a former protégé of Pym’s who has developed his own version of the Ant-Man technology and created the alter ego Yellowjacket. Pym and Lang’s attempt to steal the Yellowjacket suit is both assisted and complicated by Lilly’s Hope Van Dyne. “She’s not been in her father’s life for a long time,” Lilly says. “So her arc in the movie—as Scott’s is with his daughter—is trying to find a relationship.”

If this is all sounding a bit too “family drama” for a Marvel movie, don’t stress. There’s shrinking! Cool shrinking, Reed promises. “What we’re doing is very different from Honey, I Shrunk the Kids,” he says. “It’s going to be much more experiential.” Instead of having actors perform with outsize props, Ant-Man is utilizing both macro photography—the filming technique used on bug documentaries—and motion-capture technology. “There are cameras and lenses that make small areas look like the most epic landscapes,” says co-producer Brad Winderbaum. “Then we’re shooting motion capture with Paul to insert Ant-Man into those environments.”

About that motion capture: Rudd was bummed by the lack of balls. “I thought, ‘Oh, I’m going to get to wear one of those suits that has Ping-Pong balls on it,’” he says. “There are no Ping-Pong balls, just dots. The technology has advanced.” He was pretty wowed when he saw the test scenes, however. “It was mind-blowing,” he says. And surreal, adds Stoll—he also did time in the suit. “The director shouts out, ‘And now you’re gonna get punched on the left side of your face!’ ‘And now there’s a swarm of ants!’” he says. “It was a lot of fun.”