Equinox (1970) The Movie That Inspired The 'Evil Dead' Film Franchise

30yo teenagers summon stop-motion demons with a 'book of the dead'.
Sam Raimi was reluctant for years to admit he plagiarized this film for his 'Evil Dead' movies, but it's blatantly obvious upon viewing.
Plot:
Four teenagers go on a woods hike and encounter a creepy forest ranger and a crazy old man. The old man is a scientist who had found a mysterious book bound in human skin, the Necronomicon, and when he had read its cryptic symbols, it conjured monsters into existence. The teenagers keep the book, and are then pursued by monsters and demons.