We didn’t see this one coming. But then, again, when it comes to the Black Widow, you almost never do. Marvel’s deadliest assassin caught the world by surprise on Tuesday morning with the release of the first official trailer for Black Widow. As the first movie in the Marvel Cinematic Universe’s Phase Four lineup, the Natasha Romanoff solo film will dive into the history of a hero who gave her life in Avengers: Endgame. And based on one detail from the trailer, it seems she may encounter at least one other Avenger along the way.

In a jam-packed 2-minute video that introduces multiple alumni from the Red Room training facility that created Black Widow (Florence Pugh as Yelena Belova and Rachel Weisz as Melina Vostokoff), along with the Red Guardian (David Harbour) and Taskmaster (?), one tiny Easter egg stands out.

As Natasha infiltrates a wintry Russian military base, we see her wearing a white spy suit designed to blend into the surroundings. It might seem unimportant, but that white suit could reveal a lot about the plot of Black Widow and which comics inspired it.

Disney actually revealed Natasha’s new spy suit back at the D23 expo, where it was on display behind a glass case. Based on that reveal, we know it features a similar built as her classic black outfit, including tasers attached to her wrists and a belt holding miniature explosives, a grappling hook, and tear gas pellets. The D23 version was missing a holster for Black Widow’s signature batons, but the trailer reveals that they’re strapped to a device on her back.

To figure out the importance of the costume change, however, we’re going to have to dive a little deeper. As fans have pointed out, we’ve seen this Black Widow spy suit before in a comic book series called Black Widow: Deadly Origin, which, as the name implies, explores the character’s past as a Soviet assassin.

That alone is a pretty neat throwback, but it could just be setting up another big reveal. In Deadly Origin, Black Widow encounters various other Marvel characters who were around at that time, including none other than the Winter Soldier.

Is it possible the Winter Soldier could show up in Black Widow? We still don’t know exactly when this movie takes place, though it appears to mostly slot somewhere in between Civil War and Infinity War in the MCU’s chronology. By then, Winter Soldier is on a path to redemption, but it’s pretty clear Black Widow also features multiple flashbacks, so we wouldn’t rule out a cameo entirely.

And if Winter Soldier does show up in a flashback, he won’t be the Bucky Barnes we know and love. He’ll be a cold-hearted HYDRA killing machine.

Black Widow drops into theaters on May 1, 2020.