James Gunn’s The Belko Experiment is now streaming for free on Pluto TV — and it’s not the superhero flick you’d expect from the man behind Guardians of the Galaxy and Superman. The 89-minute horror thriller, written by Gunn and directed by Greg McLean, dropped in March 2017 to a lukewarm reception. It earned $11 million worldwide on a $5 million budget, opened seventh at the box office, and landed a 55% approval rating on Rotten Tomatoes. Critics called it hollow, lacking the subversive edge needed to elevate its premise: 80 office workers trapped in a building, forced to kill two people every 30 minutes or face execution. The voice over the intercom doesn’t just threaten death, it weaponizes fear, turning coworkers into suspects, allies into enemies, and silence into a weapon. John Gallagher Jr. Plays Mike Milch, a quiet employee caught in the chaos. Tony Goldwyn is Barry Norris, the COO whose calm facade cracks under pressure. Adria Arjona, Melonie Diaz, and John C. McGinley round out a cast that tries hard but never quite escapes the film’s mechanical rhythm. Collider reports the movie was added to Pluto TV on October 1, 2026, making it accessible to anyone with an internet connection and a taste for low-budget dread. No fanfare. No re-release hype. Just a forgotten genre experiment, suddenly free. And for those who’ve been waiting for a reason to revisit a cult-of-one horror film, this is it. The question isn’t whether it’s good. It’s why it took nearly a decade for a James Gunn project to find its audience on a free platform. But if you’re looking for something that feels like a twisted corporate retreat meets Battle Royale, with a dash of Squid Game before the trend existed, here it is. Streaming now. No subscription. No guilt. Just 89 minutes of people screaming at each other in an elevator.