Warning: Spoilers ahead for Spider-Man: Brand New Day.

• Spider-Man: Brand New Day* is now in theaters, and fans finally have a long-awaited answer to one of the biggest pre-release questions: Who is Sadie Sink playing in the film?

Sink, known for her breakout role as Max Mayfield on Netflix’s Stranger Things, was first attached to join Tom Holland’s fourth standalone Spider-Man film in March 2025, though her role was kept under wraps. Since her casting, the persistent rumor was that Sink would be playing X-Men's Jean Grey, the powerful telepath previously portrayed on the big screen by Famke Janssen in the original X-Men films and later by Sophie Turner in X-Men: Apocalypse and Dark Phoenix.

Sink remained tight-lipped throughout the Brand New Day press tour, even poking fun at the secrecy in videos posted on the film’s official Instagram and X accounts.

If you missed musician Steve Lacy accidentally spoiling Sink's character at the film's Los Angeles premiere on Monday, or you're just looking for more context, here's a full breakdown of her role.

Sadie Sink Plays Jean Grey In ‘Spider-Man: Brand New Day’

The rumors are true: Sink is playing the iconic X-Men character Jean Elaine Grey.

For a chunk of Brand New Day, Jean is believed to be the villain. The teenage telepath possesses unsuspecting people and uses them to attack Department of Damage Control (DODC) facilities. Her motives are initially unclear, but she’s viewed as an uncontrollable threat, prompting Peter Parker/Spider-Man to team up with the police and Bill Metzger (Tramell Tillman), the DODC’s director, to stop her.

After Jean is taken into DODC custody, Peter discovers that Bill has been lying to him all along and is the film’s true antagonist.

Jean and her sister Sara (Olivia Booth-Ford), also a telepath, were abandoned by their mom after their powers manifested. The siblings stuck together until Bill and the DODC kidnapped Sara. Sara was held by the DODC for "study and observation" — in reality, experimentation and torture — as the agency attempted to identify the source of her powers, record her brain activity and replicate her abilities in others.

Jean bounced between foster homes and psychiatric hospitals before eventually running away and erasing her identity from databases. Sara, however, remained imprisoned by the DODC and ultimately died during the agency's experiments.

What Happens To Jean, And When Will She Return?

Bill attempts to continue that research with Jean, who proves to be even more powerful than her sister.

When Jean learns that Sara died in the very facility where she's being held, she unlocks a new level of her abilities, expanding the range of her telepathic jumps and placing everyone within a one-kilometer radius of the Roosevelt Island facility under her psychic control.

She breaks free from the experimentation chair and threatens to kill Bill, but Peter intervenes. He allows Jean to enter his mind and witness a key memory of Aunt May (Marisa Tomei), who tells him that he’s special, but that his gifts can be isolating and make him a target for people capable of monstrous acts. She reminds Peter that the people who love him do so because of who he is, and that his greatest responsibility is to never lose sight of that, no matter how powerful he becomes.

The memory profoundly affects Jean, and Peter reminds her that she’s not alone — she has him.

Suddenly, Frank Castle/The Punisher (Jon Bernthal) fires a shot at Jean in an attempt to break her psychic hold over the civilians. Using his Spider-Sense, Peter detects the bullet and shields Jean. The gunshot critically wounds him, but Jean uses her telepathic abilities to keep him alive in the hospital. She is last seen on a bus to an undisclosed destination.

Since Disney's acquisition of 21st Century Fox, Marvel Studios has gradually begun introducing X-Men characters into the MCU, including Charles Xavier/Professor X (Patrick Stewart) in Doctor Strange in the Multiverse of Madness and Dr. Hank McCoy/Beast (Kelsey Grammer) in the mid-credits scene of The Marvels.

Sink’s role in Brand New Day marks the most significant X-Men character inclusion in the MCU to date. Several original X-Men actors — including Grammer, Ian McKellen, Patrick Stewart, James Marsden, Alan Cumming and Rebecca Romijn — are also confirmed to reprise their roles in Avengers: Doomsday.

Doomsday, in theaters on December 18, follows heroes from three different universes as they face a new existential threat. It’s unclear whether Sink will appear in the film, though it’s reasonable to expect she’ll return in Marvel Studios’ in-development X-Men reboot, directed by Jake Schreier (Thunderbolts*).