Mega Snake begins with the protagonist, Les Daniels, at a wedding. The custom at this wedding is to pass around venomous snakes, which Les is terrified of. Les hesitates getting the snake from his father, which causes the reptile to bite the father's artery, causing him to die. Twenty years later, Les is even more afraid of snakes, a fact that his older brother teases him over. To get over it, Les goes to see a Native American snake expert, Screaming Hawk. Here he is introduced to Unteka, a snake that is about the size of a common worm snake. Screaming Hawk tells Les that the snake grows to exceptional size and has killed most of his tribe. He also tells Les to never, under any circumstances, let the snake out of the jar. Les steals the snake and takes it home. Back at Les' home, the jar is smashed and the Unteka starts growing at a massive rate. Unteka decides to go on a killing spree, eating everything in his path. Les meanwhile quickly begins organizing efforts with his friends to try to track down Unteka before it kills even more people. The snake is heading straight for the county fair, where many people have come to see Feedback, the winner of the "Who Wants to be a Superhero" contest. After the snake arrives at the fair, it begins killing more people. However, Screaming Hawk arrives and quickly leaps into action. He runs to the snake and lets it eat him. As it does, Screaming Hawk pulls out a knife and manages to kill the snake from the inside. Les quickly cuts a hole in the snake and rescues his girlfriend, who had been eaten by the snake.