A movie doesn't need a monster or an ax murderer to be terrifying. Netflix released the trailer for "Brain on Fire" on Wednesday, and the film looks plenty frightening even without an obvious villain.

Based on a true story, the film follows Susannah Cahalan (Chloe Grace Moretz), a writer for the New York Post whose life is going well until some very scary symptoms start popping up. The trailer shows her health taking a turn, and then doctors being completely stumped as to what's going on. Susannah is diagnosed with a variety of mental health conditions by different physicians, and it's only when one particular doctor shows up that it starts to look like there may be hope.

Watch the trailer below.

Directed by Gerard Barrett, the film stars Moretz, Jenny Slate, Thomas Mann, Tyler Perry, Carrie-Anne Moss, and Richard Armitage.

"Brain on Fire" debuted at the Toronto International Film Festival in September 2016, and it will be released via Netflix June 22.