Three 12-year-old kids discover a Mummy (undead) 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, Bruce, they discover that if the mummy is not put back in his coffin before midnight on Halloween, the mummy will cease to exist.
This contemporary comedic remake of the 1997 Halloween classic of the same name follows three 12-year-old friends, Marshall, Gilbert and Amy. They happen upon and awaken a mummy, which they affectionately name Harold, and must rush to return him to his resting place before midnight on Halloween. Along the way, the team narrowly escapes a nefarious group of criminals intent on selling the mummy to the highest bidder. When Harold is inevitably captured, Marshall, Gilbert and Amy must band together to stand up to the criminals, face their fears and rescue their new—but rather “ancient”—friend.
Marshall, Gilbert and Amy are getting ready to attend Amy’s father’s Spooktacular Halloween-themed wedding to his fiancé Carl. However, plans soon go awry when the three friends discover their mummy pal Harold and his beloved Rose may be in danger. Sobek, an evil mummy with a 1000-year-old grudge against his best friend-turned-bitter-rival Harold, is unexpectedly awakened and out for revenge. With help from his hypnotized lacky Larry, Sobek kidnaps Rose. Gilbert, Marshall, Buzzy and Harold must use their skills once again to save her and get back in time to attend the wedding.