Robbie and his sister Alesha are visiting their Grandpa John at his cabin in the woods, which they don't want to go because they hate his scary stories that keep them up at night. He tells a story about Full Moon Fever, a mythical illness which turns anyone who looks at the full moon into ravenous, snarling beasts. He heard about it from a woman he met after getting lost in the Canadian wilderness. After he pretends to have caught it as a joke, they brush the whole thing off and try to forget about the story.