Double, Double, Toil and Trouble is a 1993 American Halloween made-for-television children's film. It stars Mary-Kate and Ashley Olsen as two adventurous little girls who discover that their Great Aunt Sophia has been trapped and cursed by her evil twin sister Agatha. On the 7th year of her imprisonment, Sophia will be doomed to the netherworld unless the curse is broken by the magical spell of twins. The film's title is part of the famous line spoken by the three witches in Shakespeare's Macbeth (Act IV, Scene I): "Double, double toil and trouble; Fire burn and cauldron bubble."
Plot
7-year-old Kelly (Mary-Kate Olsen) and 7-year-old Lynn Farmer's (Ashley Olsen) parents, Don (Eric McCormack) and Christine (Kelli Fox), are deeply in debt and in danger of losing their home. During the Halloween season, they visit Christine's cold and cruel Aunt Agatha (Cloris Leachman) to ask for a loan, which is immediately refused. While the girls wait outside, they meet Agatha's grave digger (Wayne Robson) who tells them the story of Agatha's twin sister Sophia (also played by Cloris Leachman) who is trapped inside the house. He explains to the girls that Agatha's home once belonged to a powerful witch who, before being burned at the stake 200 years before, had hidden her moonstone, the rare gem which gave her power. As children, Agatha and Sophia, tired of being twins, heard the tale and began looking for the stone in hopes of using its power to no longer look like each other. Agatha found the moonstone but hid it from her sister and instead began using the magic it possessed to make her sister's life miserable. Years later on Halloween, Sophia and her fiancé George (Matthew Walker), now Agatha's butler, prepared to elope and begin their life together, but Agatha, out of jealously and rage, cast a spell that banished her sister into the netherworld through a mirror, which she keeps hidden in the attic. On the 7th year at midnight, this Halloween, the spell will become permanent and there will be no way for Sophia to be rescued.
Back at home, Kelly and Lynn learn of their parents' financial problems. Christine expresses that if Aunt Sophia were still around, she would be able to help them. Knowing this, the girls begin a rescue mission to free Aunt Sophia before it is too late. The spell can only be broken by twins who have possession of the moonstone, so Kelly and Lynn's ultimate goal is to apprehend it. The only problem is, Aunt Agatha wears the gem around her neck at all times. While out trick or treating, they swap costumes with two other kids so they are able to get away from their parents. The first person they meet is a homeless man who dreams of money and stardom, Mr. N (Meshach Taylor), who offers to help the girls because they should not be on such a dangerous journey without an adult. The girls carry with them a toy magic wand that they won at a Halloween party, which actually has unexplained genuine magical powers (though it is heavily implied that the twins have the magical powers and not the wand). Kelly, Lynn and Mr. N visit a phony psychic to ask where they are able to find the witches gathering that Aunt Agatha will attend that night. Lulu is unable to answer and instead they use the wand to find the location and set off again by hitching a ride on a pumpkin truck. They get dropped off near a woods and find a small house deep inside, the home of a man named Oscar (Phil Fondacaro) who wishes to be taller. They tell him the whole story and he agrees to go along with them. Meanwhile, Don and Christine discover the girls have gone and inform the police.
Aunt Agatha overhears the girls' plan using the magic mirror and begins a plan to get rid of them. She is threatened by their presence because she knows that the power of twins combined is superior to her own. Kelly, Lynn, Mr. N and Oscar turn up at the gathering in costumes in hopes of fitting in and they oversee the events inside. Aunt Agatha reveals the story of her spell on her sister to the crowd while Mr. N and Oscar create a plan to try to get her to hand over the moonstone, which she does, intrigued by their promise to double her power. However, they are soon found out and are chased through town. They decide to split up; Lynn, who has the moonstone, with Oscar, and Kelly goes with Mr. N.