The first movie introduces us to Marnie Piper, a teenage girl who discovers on her 13th birthday that she comes from a family of witches. Her grandmother, Aggie Cromwell, is a powerful witch who lives in Halloweentown, a magical realm inhabited by various supernatural creatures.
Marnie, her brother Dylan, and her sister Sophie embark on an adventure to Halloweentown, where they learn about their magical heritage. They also discover that an evil warlock named Kalabar is threatening both Halloweentown and the mortal world.
Marnie and her family must use their newfound magical abilities to stop Kalabar and save both worlds.