We’ve known for a while now that Captain America: Civil War will be taking a few liberties with Marvel Comics’ source material since some of those plot specifics won’t work in the established MCU. The latest rumor may shed more light on how the story is changing from page to screen, as well as the inciting incident that creates a rift among the Avengers.

Marvel previously released this official synopsis for Captain America: Civil War, teasing a mysterious international incident:

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.

In the Civil War comics, that incident involves the New Warriors, who inadvertently destroy several city blocks and kill hundreds of civilians in their attempt to bring down a super-villain. According to Heroic Hollywood, Captain America: Civil War appropriately changes the New Warriors to the Avengers, which makes more sense for the MCU narrative.

The incident in question will involve Captain America and Scarlet Witch, who team up to take down Frank Grillo’s Crossbones, who has a suicide vest equipped with incredibly powerful explosives. Scarlet Witch uses her powers to try and keep the explosives from hurting anyone, but she ultimately fails and many innocent people lose their lives.

In the comics, the incident triggers the government to develop the Superhero Registration Act, which requires all superheroes to register with the government and publicly reveal their identities — this doesn’t work in the MCU, where many of their identities are already publicly known. The MCU’s answer to this is the Sokovia Accords, hinted at briefly in the Ant-Man post-credits scene when Cap tells Falcon that Iron Man probably can’t assist them with Bucky / Winter Soldier because of “the Accords.”

As far as rumors go, this one seems pretty sound — it would explain Frank Grillo’s brief time on set as Crossbones, at the very least.

Captain America: Civil War hits theaters on May 6, 2016.

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