If you thought there were a lot of characters in Avengers: Age of Ultron, you ain’t seen nothin’ yet.

Over the next 12 months, Marvel Studios will release two new superhero films. The first, Ant-Man, is the end of the studio’s “Phase Two” slate of movies that began with Iron Man 3 back in 2013 and reached its crescendo with Age of Ultron. As far as we know right now, that film will be a relatively self-contained superhero story that will introduce the titular insect-sized hero to the Marvel Cinematic Universe.

After that, though, comes Captain America: Civil War, a movie so big that it’s almost a third Avengers film. We’ve known the film’s title and its basic premise — Captain America (Chris Evans) and Iron Man (Robert Downey Jr.) are locked in an ideological battle with the fate of The Avengers at stake — for some time, but thanks to a Marvel press release today, we now have an official synopsis and a very, very long cast list that includes almost every Marvel superhero we’ve seen so far, and then some.

First, the synopsis:

“Captain America: Civil War” picks up where “Avengers: Age of Ultron” left off, as Steve Rogers leads the new team of Avengers in their continued efforts to safeguard humanity. After another international incident involving the Avengers results in collateral damage, political pressure mounts to install a system of accountability and a governing body to determine when to enlist the services of the team. The new status quo fractures the Avengers while they try to protect the world from a new and nefarious villain.

Obviously, Evans has the title role here, but the film will also star Downey and returning Avengers Black Widow (Scarlett Johansson), Hawkeye (Jeremy Renner), Falcon (Anthony Mackie), War Machine (Don Cheadle), Scarlet Witch (Elizabeth Olsen), and Vision (Paul Bettany), plus SHIELD’s Agent 13 (Emily VanCamp). On the villain front, we’ve got that new “nefarious villain” Baron Zemo (Daniel Bruhl), Crossbones (Frank Grill), Thunderbolt Ross (William Hurt), and Winter Soldier (Sebastian Stan).

Yup, that’s a massive cast, but we’re not done yet. The film will also feature the debut of Marvel superhero Black Panther (Chadwick Boseman), and the second big-screen appearance of Paul Rudd as Ant-Man Scott Lang. Plus, The Hobbit star Martin Freeman has joined the film in a still-unconfirmed role, but the rumor machine is already hard at work trying to find out who he’s playing.

If you’re doing the Marvel movie math, that cast includes pretty much every major player except Thor, Hulk, Nick Fury, and the Guardians of the Galaxy (who’ll be getting their own movie sequel in 2017). Basically, everyone except for The Winter Pam.

Depending on how Marvel executes it, this film has the potential to be the biggest superhero movie ever, topping even Warner Bros.’ 2016 release Batman v Superman: Dawn of Justice. And it’s not even the biggest movie Marvel’s got on their slate for the next four years.

Captain America: Civil War arrives May 6, 2016.