Shelley Duvall Seen In Movie 'The Forest Hills,' Last Project Before Death

Legendary actress and iconic horror star Shelley Duvall made a thrilling comeback in the gory indie flick "The Forest Hills" before her July death -- her first acting gig 22 years after announcing her retirement.

Just in time for Halloween season, the movie's newly released trailer unveils the chilling tale of a man haunted by nightmarish visions of becoming a werewolf, and his strained relationship with Mama -- played by Duvall -- after suffering head trauma camping in New York's Catskill woods.

Shelley told the New York Times earlier this year she'd been itching to return to acting after her 2002 retirement ... and when director Scott Goldberg kept hitting her up about his new project, she decided to sign up.

Shelley had limited mobility during filming and was using a wheelchair ... the crew wanted to work with her so desperately they brought the set to her Texas home and worked her lack of mobility into the character.

REMEMBERING SHELLEY DUVALL

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The movie hits select theaters in the U.S. and Canada on October 4th ... and you can already pre-order special "Mama" and "Billy" Edition Blu-rays.

Shelley died at 75 in July after a tough battle with diabetes ... passing away in her sleep.