Onslaught: Cast, Story, Release Date, Reviews, and Movie Guide

Onslaught is a violent 2026 action-horror movie directed by Adam Wingard and written by Simon Barrett. The filmmaking duo behind You’re Next and The Guest reunite for another dark, stylish genre story involving secret military experiments, genetically engineered super soldiers, and an ordinary community caught in the middle of a government disaster.

Adria Arjona leads the film as Celeste, a single mother and former Army sniper who lives in an isolated desert trailer park with her young daughter. When three experimental soldiers escape from a hidden facility, Celeste must use the combat skills she tried to leave behind.

The movie also stars Dan Stevens, Rebecca Hall, Drew Starkey, Michael Biehn, Eric Wareheim, Reginald VelJohnson, and UFC champion Alex Pereira. Released by A24, Onslaught opened in theaters on September 4, 2026.

Onslaught Movie Details

What Is Onslaught About?

The story follows Celeste, an Army sniper veteran attempting to raise her daughter in a remote desert community. She lives in a rundown trailer park, far away from the military world that shaped her into an expert marksman.

Although Celeste has returned to civilian life, she continues to live with the psychological effects of her service. Her post-traumatic stress can cause physical tremors, making it difficult for her to control her hands during moments of intense pressure.

Her quiet but imperfect life is destroyed when a secret military experiment escapes from a nearby government facility.

A group of genetically engineered super soldiers has been designed to operate without normal human limits. They are physically powerful, extremely difficult to kill, and trained to eliminate anyone who stands in their way. Once the soldiers break loose, they begin moving through the surrounding desert and toward Celeste’s community.

A mercenary cleanup team is sent to contain the situation, but its mission is not necessarily to protect local residents. The people responsible for the experiment are more concerned with preventing the truth from becoming public.

Celeste quickly realizes that waiting for the authorities will place her daughter in even greater danger. To protect her family and neighbors, she retrieves her weapons and returns to the combat instincts she has spent years trying to control.

The official A24 synopsis describes the movie as a fight between a highly skilled mother and a rogue squad of super soldiers. However, the story also examines what happens when a government treats both its soldiers and its poorest communities as disposable resources.

Adria Arjona as Celeste

Adria Arjona plays Celeste, the central character in Onslaught.

Celeste is an experienced sniper, but she is not portrayed as an emotionless action hero. She carries psychological wounds from her military service and struggles with symptoms of PTSD. Those symptoms become especially dangerous when she must once again handle firearms under pressure.

Arjona worked to give Celeste a physical behavior that would communicate her internal distress without lengthy explanations. Whenever a tremor begins affecting her ability to shoot, Celeste presses an old ring into her forearm. The pain helps her focus on the immediate moment.

In an interview with People, Arjona explained that the detail grew from discussions about how the character might manage her trauma. The ring is missing its stone, suggesting Celeste may have sold it during a difficult period in her life.

It is a small detail, but it separates Celeste from the unstoppable heroes often found in military action movies. Her skills do not erase her pain. Every violent confrontation forces her to reopen a part of herself she would rather leave buried.

Arjona also serves as an executive producer on the movie. Her involvement gave her a greater role in shaping Celeste’s personality, emotional history, and physical presentation.

Before filming, she trained with stunt performers, former military personnel, weapons experts, and the production’s armorer. She learned how to handle sniper rifles, move through combat situations, and operate a chainsaw safely.

Her previous roles in Andor, Hit Man, The Belko Experiment, and Blink Twice prepared her for the combination of action, humor, and horror. However, Onslaught gives Arjona one of her most physically demanding leading roles.

Dan Stevens as Dr. Kammler

Dan Stevens portrays Dr. Hans Kammler, a scientist connected to the experimental super-soldier program.

Kammler represents the intellectual side of the movie’s threat. The escaped soldiers may carry out the violence, but scientists and government officials are responsible for creating them.

Stevens has become a regular collaborator with Adam Wingard. He starred as the mysterious David Collins in The Guest and later played the eccentric veterinarian Trapper in Godzilla x Kong: The New Empire.

His performances often combine charm, menace, and strange humor. That makes him well suited to a scientist whose professional confidence hides deeply disturbing ideas about warfare and human experimentation.

Kammler appears to view the soldiers as products rather than people. Their bodies, memories, and moral instincts can be altered if doing so creates a more effective weapon.

The character also strengthens the connection between Onslaught and The Guest, another Wingard-Barrett movie built around an experimental military program that transforms human beings into nearly unstoppable killers.

Rebecca Hall as Frau Kammler

Rebecca Hall plays Frau Kammler, another scientist associated with the program.

Like Dan Stevens, Hall previously worked with Wingard on Godzilla x Kong: The New Empire. Her role in Onslaught allows her to embrace the story’s stranger and more exaggerated side.

Frau Kammler is involved in the conspiracy surrounding the escaped experiments. Her composed appearance and scientific authority contrast with the bloody destruction caused by the soldiers.

Hall has experience with both thoughtful drama and genre filmmaking through movies such as The Night House, Resurrection, The Prestige, and Godzilla vs. Kong. She can make a character feel intelligent and controlled while suggesting that something far more dangerous exists beneath the surface.

Alex Pereira as The Butcher

UFC champion Alex Pereira makes his major feature-film acting debut as The Butcher, one of the movie’s most physically intimidating characters.

The Butcher is part of the super-soldier threat pursuing Celeste and her daughter. Pereira’s background as a professional mixed martial artist gives the character an authentic physical presence that would be difficult to create entirely through visual effects.

Wingard does not need to rely on lengthy dialogue to establish The Butcher as dangerous. Pereira’s size, movement, and fighting experience communicate the threat immediately.

The character functions partly like a slasher villain. He continues advancing through gunfire, injuries, and increasingly violent obstacles. Instead of a masked killer stalking teenagers, however, the movie presents a military weapon moving through a desert community.

That combination of super-soldier action and slasher horror defines much of the film’s style.

Michael Biehn as Baylor

Michael Biehn plays Baylor, the leader of a mercenary unit sent to control the situation.

Biehn is one of the most recognizable actors in science-fiction action cinema. His major roles include Kyle Reese in The Terminator, Corporal Hicks in Aliens, and Lieutenant Coffey in The Abyss.

Casting him in Onslaught creates an immediate connection to the practical, hard-edged action movies of the 1980s and 1990s. Baylor feels like someone who belongs to that cinematic tradition.

However, his team’s priorities may not align with Celeste’s. The mercenaries are responsible for containing the escaped soldiers and protecting the secrecy of the program. If innocent witnesses become a threat to that mission, Baylor may consider them expendable.

Drew Starkey as Cyrus

Drew Starkey plays Cyrus, a character drawn into the conspiracy surrounding the escaped experiments.

Starkey is known for Outer Banks, Queer, and The Other Zoey. His appearance in Onslaught moves him into a more violent and unusual genre environment.

Cyrus brings unpredictable energy to the story. While Celeste is direct and survival-focused, he belongs to the stranger network of people attempting to control, study, or clean up the government experiment.

His character also adds dark humor to a movie that might otherwise become overwhelmingly grim.

Eric Wareheim and Reginald VelJohnson

Eric Wareheim plays Kovacks, a member of the trailer park community. Wareheim’s distinctive comedy style contributes to the movie’s deliberately odd supporting cast and moments of absurdity.

Reginald VelJohnson portrays Josiah, another local resident caught in the attack. VelJohnson is best known for playing police officer Al Powell in Die Hard and Carl Winslow in Family Matters.

Both actors help establish the trailer park as a genuine community rather than an anonymous location waiting to be destroyed. Celeste is not only protecting her daughter. She is defending people with whom she has built relationships.

The complete cast listed by A24 includes Adria Arjona, Dan Stevens, Eric Wareheim, Reginald VelJohnson, Michael Biehn, Alex Pereira, Drew Starkey, and Rebecca Hall.

Who Directed Onslaught?

Adam Wingard directed Onslaught. His filmography moves between independent horror movies and enormous studio productions.

Wingard first gained widespread attention with You’re Next, a home-invasion thriller that combined brutal violence with dark comedy and a capable female protagonist. He followed it with The Guest, Blair Witch, and the live-action adaptation of Death Note.

He later entered the MonsterVerse, directing Godzilla vs. Kong and Godzilla x Kong: The New Empire. Those movies gave him experience creating large-scale battles and visual-effects spectacles.

Onslaught represents a return to a smaller and dirtier style of filmmaking. Instead of giant monsters destroying cities, the movie follows one mother defending a trailer park from a handful of deadly opponents.

The reduced scale does not mean less action. It allows Wingard to place the camera closer to the violence and emphasize practical stunts, physical environments, weapons, and gore.

The movie was written by Simon Barrett, Wingard’s longtime creative partner. Barrett also wrote You’re Next, The Guest, and Blair Witch. Their collaborations are known for mixing familiar genre ideas with unusual characters and sudden changes in tone.

Is Onslaught Connected to The Guest?

Yes, Onslaught is connected to The Guest, although it is not a traditional direct sequel.

The Guest followed David Collins, a former soldier whose polite behavior concealed his connection to an experimental military program. The movie gradually revealed that David had been psychologically and physically altered, turning him into an extremely effective killer.

Onslaught expands on a similar idea. Its rogue soldiers come from a program that attempts to remove normal human limitations and create controllable weapons.

Current interviews describe the film as a covert spinoff or companion story set within the same broader universe. It does not require viewers to remember every event from The Guest, and Adria Arjona’s Celeste is the main character rather than Dan Stevens’ David.

However, fans of the earlier movie will notice thematic and story connections involving military experimentation, secret cleanup operations, enhanced soldiers, and government agencies willing to kill civilians to protect their work.

The presence of Dan Stevens makes the relationship even more playful, although he portrays a different character in Onslaught.

New viewers can follow the movie without watching The Guest. Watching both films, however, provides more context for the type of conspiracy Wingard and Barrett are building.

How Onslaught Mixes Action and Horror

Onslaught has been described as a super-soldier slasher.

The escaped experiments function like science-fiction weapons, but Wingard films them with the persistence and physical menace of classic horror villains. They do not simply attack Celeste once and disappear. They continue hunting her across the desert, forcing each confrontation to become more desperate.

The movie also borrows from grindhouse cinema. Its violence is exaggerated, its scientists are deliberately strange, and its characters sometimes respond to horrifying situations with unexpected humor.

Practical blood effects play an important role. Arjona revealed to Men’s Health that filming took place in extremely cold conditions, requiring the effects team to modify the fake blood so it would not freeze against her skin.

The production used real locations rather than making every environment look clean and artificial. Celeste’s home was filmed in a genuine worn-down trailer park, giving the movie a dusty and lived-in texture.

That setting creates a strong contrast with the laboratory technology behind the super soldiers. Advanced military weapons enter a community that barely has the resources to protect itself.

Onslaught Release Date and Where to Watch

Onslaught opened in United States theaters on September 4, 2026.

As of September 5, the movie is now playing theatrically. Tickets and participating locations are available through the official A24 movie page.

The film is not currently available through a subscription-streaming service. A24 has opened digital preorders through services including Apple TV, Amazon, and Fandango at Home, but an official digital release date has not been confirmed.

Viewers interested in watching it immediately will need to find a theatrical screening.

Runtime and Age Rating

Onslaught has a runtime of 92 minutes, making it a relatively compact action movie.

It is rated R for strong bloody violence, gore, sexual material, nudity, and language. The rating reflects the film’s combination of military combat, slasher-style attacks, practical blood effects, and adult content.

This is not a superhero-style adventure suitable for younger viewers. It was designed as a violent, exaggerated genre movie for mature audiences.

Onslaught Reviews and Rotten Tomatoes Score

Critical reaction to Onslaught has been divided.

As of September 5, 2026, the movie holds a 53% critics’ score on Rotten Tomatoes, based on 98 reviews. Its verified audience score is 63%, based on more than 100 ratings. These numbers may continue changing as additional viewers see the film.

The Rotten Tomatoes overview praises the stylish action, practical gore, and old-school genre energy. However, its consensus also suggests that the story does not always provide the emotional or thematic power promised by its aggressive title.

Positive reviews have highlighted Adria Arjona’s committed performance, Wingard’s visual direction, the unusual supporting cast, and the movie’s short runtime. Fans of You’re Next and The Guest may also appreciate seeing Wingard and Barrett return to smaller-scale horror.

More negative responses argue that the plot is too thin, the political ideas are underdeveloped, and the movie does not push its violent premise far enough. Some critics expected a more outrageous grindhouse experience from a film named Onslaught.

The divided reaction means the movie’s appeal will depend heavily on expectations. Viewers seeking deep science-fiction world-building may find it limited. Those interested in a fast, bloody battle between a sniper and experimental killers may have considerably more fun.

Who Should Watch Onslaught?

Onslaught is likely to appeal to viewers who enjoy:

• Adria Arjona’s action performances
• Adam Wingard and Simon Barrett collaborations
• Movies such as The Guest and You’re Next
• Genetically engineered super-soldier stories
• Slasher movies with science-fiction elements
• Practical effects and exaggerated movie violence
• Compact action thrillers with minimal downtime
• A24’s more commercial genre releases
• Michael Biehn’s classic action-movie presence

The movie is built around a simple but effective idea: a mother with specialized military training must defend her child from weapons created by the institution that trained her.

That personal conflict gives Onslaught something more compelling than its body count. Celeste is not returning to violence because she misses it. She returns because the people who created these killers have left her family with no other means of survival.