12-year-old friends, Marshall, Gilbert and Amy accidentally revive a mummy they discover in a neighbor's basement. They affectionately name the mummy Harold, and must rush to return him to his resting place before midnight on Halloween.
While Amy is preparing for her father's Halloween-themed wedding, she, Gilbert and Marshall discover that Harold and Rose may be in danger. An evil mummy is unexpectedly awakened and out for revenge.
George falls for the cute guy she's assigned to train at Happy Time, much to Delores' chagrin. Mason's reap at a children's birthday party turns out to be his worst experience ever.