It turns out the Demagorgon isn’t the biggest threat in the Stranger Things universe. The Duffer Brothers are being sued for plagiarism.

The Netflix series Stranger Things has been a mega-hit for the streaming service. It’s not surprising, as the series has been one of the most inventive, refreshing new series on television. However, as a recent lawsuit being brought up against the Duffer Brothers (the Stranger Things creators) claims, it might not be as original as we all thought.

Related: Stranger Things haunted house coming to Universal’s Halloween Horror Nights

According to Variety, the Duffers are being sued for plagiarism by the director of a short film called Montauk. Montauk was a six-minute film made by Charlie Kessler about strange happenings surrounding a real government base in Mantauk, Long Island called Camp Hero.

According to Kessler, the short film was made up of found footage focusing on the supernatural fallout from government experiments and was a teaser for a feature film he intended to make called The Montauk Project. He allegedly pitched the film to the Duffers back in 2014, but nothing came of their conversations (or so he thought).

Of course, Stranger Things is also a story about supernatural consequences of government experiments, and was even initially sold to Netflix as Montauk, and was initially set in Long Island.

However, Kessler isn’t the only one to have written about the supernatural occurrences around the Long Island government base. In 1992, there was a book called The Montauk Project: Experiments in Time that chronicled stories from those with repressed memories from Camp Hero, and since that time stories from Montauk’s Camp Hero have frequently circulated conspiracy site.

A Vanity Fair article reports that Kessler claims his film would also focus on a missing child, monsters from another dimension, and military experiments on children, much like what is seen in Stranger Things. However, the Duffers do not employ Kessler’s original found footage angle.

It’s not clear how a judge will rule in this case, but Kessler is seeking damages and a jury trial against the Duffers. He filed with the Los Angeles Superior Court on April 3. We’ll be watching this story to see what happens next.

Had you heard about Camp Hero and Montauk before ‘Stranger Things’?