Three 12-year-old kids discover a mummy in the basement of a "dead" man's house. It comes alive due to the conjunction of the moonlight during that time of the month. They are scared of him at first, but with time discover he is friendly, if clumsy and confused.
The kids name the mummy Harold, and decide he will temporarily take up residence in one kid's bedroom. After paying a visit to their Halloween-obsessed friend, they discover that if the mummy is not put back in his coffin before midnight on Halloween, the mummy will cease to exist.
Luckily, the sarcophagus is in the Egyptian exhibit at the local museum, but there are a few obstacles. For one thing, Harold's unusual appearance may attract unwanted attention as Halloween night draws closer. Also, someone powerful and evil is out to get Harold, meaning the kids have to save him before midnight on Halloween.
- Mario Yedidia as Marshall. The main character.
- Adam Wylie as Gilbert. The second main character.
- Clara Bryant as Amy. The third main character.
- Ken Campbell as Bruce. A Halloween lover.
- Ed Lauter as Mr. Kubat. The main antagonist of the film.
- Bill Fagerbakke as Harold / Ted
- Corinne Bohrer as Marshall's Mom