An American Werewolf in London (1981)

Two American students are on a walking tour of Britain and are attacked by a Werewolf. One is killed, the other is mauled. The Werewolf is killed but reverts to its human form, and the local townspeople are unwilling to acknowledge its existence. The surviving student begins to have nightmares of hunting on four feet at first but then finds that his friend and other recent victims appear to him, demanding that he find a way to die to release them from their curse, being trapped between worlds because of their unnatural deaths.