The creators of Stranger Things have denied stealing ideas for the series.
Matt and Ross Duffer are being sued by a director who says they took plotlines from one of his short films which was released in 2012.
Charlie Kessler claims he pitched Montauk and feature film script The Montauk Project to the brothers in 2014, and later the ideas were used in Stranger Things.
The Duffer brothers have dismissed his claims as "completely meritless".
The lawsuit claims "the script, ideas, story and film" were talked about to the brothers at a party for the Tribeca Film Festival.
It says Matt and Ross Duffer have made "huge sums of money" from Mr Kessler's ideas.
He's suing for breach of implied contract and is seeking damages.
It is not clear which themes the show is said to copy.
"Mr Kessler's claim is completely meritless," The Duffer brothers' lawyer, Alex Kohner, said in a statement to the Press Association.
"He had no connection to the creation or development of Stranger Things."
The sci-fi drama, starring Millie Bobby Brown, is one of the most popular shows on Netflix.
When the first episode of season two was released in October, it gave Netflix its most popular streaming day of the year.
"The Duffer Brothers have neither seen Mr Kessler's short film nor discussed any project with him," continued Mr Kohner.
"This is just an attempt to profit from other people's creativity and hard work."