Returning from a hunting trip within the woods, the car of the Henderson family strikes on a monster in the road. At first they fear it turned into a person, but when they examine the"body" they see it's a"bigfoot". They think it's dead so that they decide to take it home (there could be some cash in that ). As you imagined, it isn't dead. Far from being the ferocious creature that they fear"Harry" to be, he's a friendly giant.