 A group of friends are sailing on the yacht when a storm blows them off course and damages the boat. They soon land on a deserted island where they find a deserted, fungus covered wreck. They then find out that it was a research vessel examining the effects of radiation on plant and animal life. However, they also discover a strange fungus dubbed Matango. They also find out that the crew ate some of the fungus and were somehow driven mad. The group then goes about trying to find food and water without succumbing to the lure of the mushrooms. However, one by one they soon are driven by their hunger and desires to eat the mushrooms with disastrous effects.