The New MutantsSave

In present-day America, a tornado destroys the small Cheyenne reservation town where Dani Moonstar (Blu Hunt) lives with her family. Dani is the sole survivor of the tornado; she awakens in a remote psychiatric facility called Milbury Hospital, run by Dr. Cecilia Reyes (Alice Braga). Dr. Reyes informs Dani that she has manifested mutant abilities — specifically, the ability to project her own subconscious fears and traumas as physical realities. Milbury Hospital is a containment facility for young mutants who have not yet learned to control their abilities.

Dani meets the other patients at Milbury Hospital: Rahne Sinclair / Wolfsbane (Maisie Williams) — a Scottish girl whose Catholic upbringing has made her ashamed of her ability to transform into a wolf; Illyana Rasputin / Magik (Anya Taylor-Joy) — a Russian girl with telekinetic and dimensional-portal abilities, also Colossus's younger sister; Sam Guthrie / Cannonball (Charlie Heaton) — a coal-miner's son with the ability to launch himself like a projectile at high speeds; and Roberto da Costa / Sunspot (Henry Zaga) — a wealthy Brazilian whose powers manifest as solar-energy-based fire and flight.

The five young mutants gradually develop relationships at Milbury — with Dani and Rahne developing a romantic bond, Illyana operating as the group's primary skeptic, and Sam and Roberto as more cautious supporting characters. The middle act of the film consists of their relationship development and gradual discovery of Milbury's true nature. Dr. Reyes, the patients eventually discover, has not been holding them as therapeutic patients but as research subjects for the Essex Corporation — a secretive organisization that has been studying mutant abilities for weaponisation.

Dani's specific mutant abilities are the film's primary source of escalating tension. Her power to project subconscious fears and traumas means that the other patients' deepest psychological vulnerabilities are gradually being made physically manifest at Milbury Hospital. Rahne's repressed religious shame becomes literal Catholic-priest figures haunting her; Illyana's childhood trauma becomes the demonic Lockheed entity; Sam's fear of being trapped in coal-mine collapses becomes physical cave-in apparitions.

Dr. Reyes's true purpose becomes clear: she has been conducting the patients' containment specifically to study how powerful their abilities might become when fully manifested. The Essex Corporation plans to capture the patients and study their abilities for weaponisation; Reyes is the project's primary scientific lead. The patients, learning Reyes's deception, attempt to escape. The escape attempt triggers Reyes's plan: she activates a containment field that traps the patients while she calls for Essex Corporation reinforcement.

The film's third-act battle takes place during Dani's manifestation of the Demon Bear — her largest-scale fear projection. The Demon Bear attacks Milbury Hospital, destroying significant portions of the facility. The patients, having overcome their personal traumas through their developing relationships, work together to defeat the Demon Bear by helping Dani consciously accept and integrate her own grief. Dr. Reyes is killed in the chaos; the Essex Corporation's plans are temporarily disrupted.

The film's epilogue shows the patients leaving Milbury Hospital together, their containment now ended. Dani, Rahne, Illyana, Sam, and Roberto walk down the hospital's main road, the morning sun rising behind them. They have not yet decided what their future will hold; their commitment to each other as a chosen family is the film's primary character-anchor element. A planned sequel was developed but never produced after the first film's commercial failure.