The film opens with the song "Trick or Treat for Halloween", the lyrics of which tell the film's moral – one must be generous on Halloween or face trouble. One Halloween night,
a witch named Hazel takes great joy in scaring
bats on a
clock tower and a
cat on
fence. But then she gets scared by a
jack-o'-lantern and hides behind a
tree. The jack-o-lantern turns out to be part of
Huey, Dewey, and Louie’s
costumes as they go
trick-or-treating. When the trio goes to their
uncle Donald Duck's house, Donald decides to
prank the boys (giving them a "trick" instead of a treat). Instead of giving them
candy, he puts
firecrackers in their bags and then pulls a string that dumps a bucket of water on their heads. After Donald bids farewell to the boys, the discouraged nephews go and sit on the
curb. Hazel, who was watching the
drama unfold, approaches the boys and when she discovers that they believe in witches, Hazel happily offers to help them get their treats from Donald. At first, she tries to kindly convince Donald but he skeptically retorts, yanks on her stretchy
nose, and dumps the bucket of water on her head, not believing she is a real witch. Realizing that the job may be harder than anticipated, Hazel tells the boys she will use her magic for this situation. In another location, a scene paying homage to
Shakespeare's Macbeth shows Hazel and the nephews concocting a
magic potion, adding somewhat more whimsical ingredients than the
Three Witches in
Macbeth (such as, "
Eye of needle, tongue of shoe,
hand of clock that
points at two!", etc.). After testing the potion, Hazel fills an insecticide sprayer (similar in appearance to a
Flit gun) with the potion and returns to Donald's house with the nephews. Upon arriving back at Donald's house, Hazel sprays the potion on an assortment of objects (a
jack-o'-lantern, a can of
paint, three
fence posts that turn into ghosts, and a
gate) causing them to become animated or
anthropomorphic. Donald, stunned at the magic being displayed before him, immediately gives in and agrees to treat his nephews, but when Hazel refers to him as a pushover, he changes his mind, locks his
pantry and swallows the
key. Hazel uses the potion on Donald's feet to give her control of their maneuverability and commands them to kick out the key, causing Donald to perform a crazy
dance while Hazel plays her
broom like a
guitar and sings to the dance. This also causes Donald to get his rear poked by a
cactus that was turned big by Hazel and
burned by the
fireplace, successfully getting the key out of his
stomach. However, Donald makes the situation worse by throwing the key under the pantry door. Enraged, Hazel casts a spell "that's double-grim!" on Donald's feet by spraying them even harder and ordering them to "smash that door down" with Donald. This is initially unsuccessful, so Hazel commands him to take a longer start, and he runs even faster right before he rams down the pantry door and is left unconscious on the floor in defeat. In the end, Huey, Dewey, and Louie collect their treats and wave goodbye to Hazel as she flies off into the night. A final shot shows the enchanted jack-o'-lantern from earlier suddenly popping onto the screen saying "Boo!" to the viewers before smiling. ==Voice cast==