An American Werewolf in London (1981)

Two American friends, David and Jack, set off on what should be a carefree hike across the Yorkshire Moors, but their trip takes a brutal turn when theyre attacked by a wild creature that no one can clearly identify. David survives the ordeal and is taken to a London hospital, where hes cared for by a kind and attentive nurse. As his body heals, his mind begins to unravel with violent dreams, hallucinations, and a creeping sense that something inside him is shifting in ways he cant control. Struggling to separate reality from nightmare, Davids fear grows that the attack has left him with more than just scars, and that the danger he now poses might be even greater than what first struck him on the moors.