One of the ghosts living in the cementery was upset because it wasn't invited to go Trick or Treat this year. The ghost wore a "bat" costume. It decided to get candies anyways. When everyone was distracted looking at the sort of skull and crossbones that suddenly appeared on the cementery ground - planted by the ghost (dressed as a bat)- it quickly stole all the candies from the large skeleton's pumpkin pail. Took off quickly and disappeared in the dark night. The only witnesses were the pumpkins but they were unable to speak.

Motive: revenge for not been invited