Peter and Judy stand in line for 2 hours for a rollercoaster, but Peter is too short and runs off, upset. Judy convinces him to play Jumanji and she gets the clue "one small trade makes fortunes rise, but what remains is just your size" before the two get sucked into Jumanji again. They end up in a field and are chased by hogs, but escape with Alan's help into a ditch. Judy and Alan easily get out, but Peter needs Alan's help to. After Alan tries (and fails) to cheer Peter up, the three head for Slick due to the clue mentioning "one small trade." There Slick tries to trade them a "divining rod" (a stick) but they don't go for it and leave except for Peter who asks if Slick has anything to make him bigger. Slick has a potion to do exactly that, and Peter trades a rabbit's foot for it and drinks some of it. Instantly Peter grows so he's a bit taller than Judy, but while hiding in a log from a lynx, Peter starts growing again. Peter grows to a height of several feet and drives off the lynx. Peter, happy drinks most of what's left of the potion wanting to be even taller, but Judy takes it from him before he can finish off the rest and they have to run from the hogs again. However, Peter grows to giant size and drives the hogs off easily. Peter gets hungry and eats bananas from a couple trees (one which damages Slick's place when he throws it, but luckily Slick has insurance) and then heads to the river for water. After taking a drink, Peter takes Alan and Judy to a mango grove across the river, but Judy wants to return Peter to normal and he refuses as he likes being big. Judy and Alan go to Slick for an antidote and while they're gone, Peter finds the Manjis under attack and tries to help them, but only makes things worse, demolishing the Manji village. Judy and Alan force Slick to give them an antidote for free and he warns them only three drops are to be taken as its extremely powerful. At the village, Peter continues his battle and does even more damage (and accidentally demolishes Slick's place with a rock that misses, but he has insurance for that too) but he loses the battle, however the Manjis drive the creature away. The Manjis, angry, tie Peter up and plan to drop him in the Pit of Doom. Alan distracts the Manjis and Judy manages to get Peter the antidote, but he drinks the whole thing and becomes very tiny while due to Tribal Bob's actions, they're suspended over the Pit of Doom. Alan saves them and Judy pretends Peter was killed, horrifying Tribal Bob as Peter was his friend and he realizes the mistake he made. Alan and Judy take Peter to Slick's to try to find a cure, but he's gone and Peter gets taken by a rat. Peter drives off the rat and Alan and Judy try to figure out how to help him. Thinking about their clue, they guess the trade part meant Peter's trade with Slick and Judy figures out that "what remains" means what's left of the giant potion. There's a drop left and using it on Peter cures him and restores him to his correct size. It also solves their clue and sends them home, but leaves Peter wondering where his left shoe is. Its shown that his shoe (still giant), which had fallen off when the Manjis caught him, is Tribal Bob's new home.