Judy is practicing her violin for a recital later that night which Peter has no choice but to go to. Against Judy's wishes, he rolls and gets the clue "fools draw ruin from the earth, the only hope is a magic birth" before the two are sucked into the game. The two land in the Jumanji Bayou and encounter Alan who is running from a giant leech monster. The three split up and the giant leech goes after Peter. He nearly gets sucked up by it, but Alan and Judy distract the leech and save him. The leech turns its attention to them, but Alan defeats it by tossing a snake he accidentally grabbed at it and the snake holds its mouth shut. After hearing Peter and Judy's clue, Alan figures it could mean the old Dirt Mines on the other side of the Bayou and heads off to find the paddles for his canoe. Peter draws a creature in the mud, which comes to life and Peter names it Mud Boy. Judy isn't too happy when she finds out about it, but they take it with them. In the canoe, Mud Boy fools around and scares Alan causing the canoe to tip over. An alligator destroys the canoe although they get safely to shore. Judy tries to impose rules on Mud Boy, but Mud Boy, who doesn't like rules, yells at her and runs off. At the dirt mines a machine attacks them and Peter gets separated from Judy and Alan and encounters Mud Boy in an underground tunnel and the two head off to find Judy and Alan. In the upper level, Judy pulls a control lever lacking any cobwebs and the two fall through a trap door into the underground tunnel and encounter a giant mole that attacks them, but Judy causes a flood that washes it away. Mud Boy reveals that he just wants to have fun and takes Peter to a place with some spongy substance and a nearby mud waterfall. The two bounce around, and then Mud Boy decides to get rid of Alan and Judy so he and Peter can have fun forever and takes off to get them after sticking Peter to a wall. Alan and Judy are nearly drowned in the mud river while Mud Boy just watches, but Peter manages to free himself and saves them. Mud Boy adds more mud to himself and grows to giant size and chases the three. Peter finally stops him by creating Mud Girl, Mud Boy's older sister and Mud Girl orders Mud Boy around like Judy does to Peter and gets him to stop. Mud Boy returns to normal and heads off with Mud Girl, but not before he gives Peter a friendly wave and appreciates what Peter put on Mud Girl for him: a kick me sign inscribed into her back. Alan realizes that Mud Boy was the "ruin from the earth" and Mud Girl was the "magic birth" thus solving Peter's clue and sending him and Judy back home. At home Peter decides to go to Judy's recital despite her saying he doesn't have to, but he wears a Walkman.