The Manji Voodoo Doll is a special tool used in healing by the Manji's witch doctor, and the focal point of the namesake episode The Doll. It can assume complete control over the patient by tying a strand of their hair around the dolls neck. However, if the doll does not have a powerful Jumanji ruby in its tummy, the voodoo will diminish and it will be useless.
When Judy and Peter enter Jumanji, Peter falls into a river below that is too fast to swim, swept away ends up washed on shore drowned and is found by Manjis who take him to their witch-doctor. The witch-doctor manages to revive Peter with a voodoo doll as Alan and Judy show up and Alan explains that the doll cures all and all that's needed is a single strand of hair. This gives Peter an idea to get some sweet revenge on people in Brantford that gave him a hard time and steals the doll which the witch-doctor discovers when an injured warrior is brought in soon after. The Manjis, angry start to chase Judy, Alan and Peter, but they manage to get away by solving their clue as Peter's songbook saved him and they return home although Judy doesn't understand what the first part of the clue meant and Peter pretends not to either.
At school, Peter gets a strand of hair the teacher dropped and makes her look like a fool in front of the class. Later, at baseball practice after the coach insults him, Peter uses the doll to make the umpire kick the coach out. When Rock comes after him, Peter uses the doll to spin him around and throw him into a trash can. At home, Peter uses it to force Aunt Nora to do his chores (and make his dinner as it turns out) and Judy catches him in the act. When she tries to stop him, Peter uses one of her hairs on the doll and puts it into the fridge, causing Judy to turn to ice. When Peter retrieves the doll, the ruby in the center falls off without Peter noticing and nothing Peter can do will revive Judy so he decides to ask the witch-doctor and he's sucked back into Jumanji alone. There, Peter's grabbed by a Lemur, but is saved by Alan. The lemur has his backpack which has the doll and it starts eating the backpack. Alan and Peter retrieve the doll, but are caught by Manjis who aren't happy to see Peter. Peter returns the doll and asks the witch-doctor to help him save Judy, but the witch-doctor is unable to help without the ruby from the doll's chest which is still in the freezer. As the Manjis have no more, Peter and Alan head to a very hot bee's nest that has rubies forming thanks to the heat and after infiltrating it wearing mud, Peter retrieves a ruby, but the two are forced to run as Peter accidentally wakes the queen. They escape and Peter gives the ruby to the witch-doctor who puts it into its place on the doll and starts to glow. Peter realizes that that solves his clue and he returns home where Judy returns to normal and is extremely angry at what Peter did to her and chases him.