Ernest P. Worrell, is working as a maintenance man at a summer camp and hoping to become a counselor. Ernest gets his chance when he is assigned a small group of juvenile delinquents. At first, the boys torment Ernest, playing practical jokes and mocking his efforts to get them interested in the outdoors. Their efforts are also met by resistance from other, more affluent campers. Meanwhile, an evil mining corporation run by the ruthless Sherman Krader has its sights on the summer camp, a site rich with the fictional mineral petrocite. However, Chief St. Cloud, the camp owner, refuses to sell. Krader manipulates the naive Ernest, one of the few people who speaks the chief's language, into convincing St. Cloud to sign away the land, believing it to be a conservation petition. Ernest decides to fix the situation by storming into the construction site and picking a fight with the foreman. Ernest is savagely beaten; however, he begins to gain the respect of his campers after the camp's doctor points out that Ernest is the only person who has defended them. Recruiting the campers, Ernest plans a full-scale assault as the construction company begins to demolish the camp.