‘Backrooms,’ A24’s record-breaking hit, debuts on HBO Max: the $10 million horror film is now streaming

“Backrooms,” A24’s microbudget horror film that became the studio’s highest-grossing movie ever with more than $400 million worldwide (from a budget of just $10 million), debuted on HBO Max on September 25, 2026, as ComingSoon reports.

The film marks the directorial debut of 20-year-old Kane Parsons, the YouTube star who adapted his viral web series about liminal spaces; he became the youngest director in history to debut a film at number one at the box office. The cast includes Chiwetel Ejiofor, Renate Reinsve, Mark Duplass, Finn Bennett and Lukita Maxwell.

According to the official logline: a strange door appears in the basement of a furniture store and leads into an endless network of interconnected rooms where time bends — and the only thing scarier than getting lost is the feeling that something is waiting for you. The screenplay is by Will Soodik, with producers including James Wan, Michael Clear, Roberto Patino, Shawn Levy, Dan Cohen, Dan Levine, Osgood Perkins, Chris Ferguson, Peter Chernin, Jenno Topping and Kori Adelson.

The context of its success is striking: the film opened to $81 million domestically — the biggest opening ever for A24 — passed “Marty Supreme” ($192 million) to become the studio’s first film to cross $200 million globally, and holds around 86–87% on Rotten Tomatoes (Certified Fresh).

With its streaming debut, the horror film that dominated cinemas this fall can now be watched by all HBO Max subscribers.