An employee at Destroido Corp is rung by a dark voiced man. The employee disgrees with the man but is pushed off a cliff by Cicadas.
Mystery Inc. get a note from Mr. E: ' theres a mystery at the hospital'. The employee is lying in the hospital bed when Mystery Inc. arrive. Sherrif explains that a Cicada make of tiny Cicadas is responsible. On TV Grandma Moonbeam advertises her new cookies. More employee have been attacked by Cicadas. The gang hop onto the lift but are now trapped in the basement, were the giant Cicada Creature is waiting. The monster says it will attack them the following night. The gang are failing at finding Clues. The new Cicada loving Destroido Corp hating man from school is a suspect so the gang find him. The sherrif and Mayor arrive. Mayor Jones tellls Fred to be at the Cicada Festival the following night to increase the number of tourists. Fred and Daphne become boyfriend and girlfriend and attempt to sneak off to the trap musuem but a suspect enters an attraction at the Cicada Fair. The creature is in there and is unmasked as Grandma Moonbeam. Moonbeam wanted to get even with Destroido for changing her recipe.