A Pulitzer-winning playwright's family is suing director Guillermo Del Toro and Fox Searchlight in a copyright suit, alleging The Shape Of Water "brazenly" copied his story.
The film, which is competing for 13 Oscars, is "in many ways identical" to 1969's Let Me Hear You Whisper by the late Paul Zindel, according to the lawsuit.
Zindel's family sued the studio, the director and others in a California court on Wednesday - as voters considered who to back at the Oscars.
Del Toro and Fox Searchlight denied the allegations about the Golden Globe-winning movie starring British actress Sally Hawkins.
But lawyer Marc Toberoff claimed there are at least 61 similarities, saying they are both 1960s Cold War stories about an unmarried janitor and her relationship with an aquatic creature in a secret laboratory.
"The Shape Of Water, though presented to the public as a highly original work of fantasy/science fiction, in reality, brazenly copies the story, elements, characters, and themes from a work by Pulitzer Prize-winning author Paul Zindel," he added.
Del Toro told industry website Deadline he has not read or seen the play.
"I'd never heard of this play before making The Shape Of Water, and none of my collaborators ever mentioned the play," he added.
Fox Searchlight said it would "vigorously" defend the "ground-breaking and original film".
Australian Associated Press