Scooby and Shaggy struggle to re-incarcerate thirteen of the foulest demons ever to plague the earth after they accidentally release the demons from a chest.

Maldor the Malevolent lures the gang into his evil forest in hopes of destroying the only ones who could jeopardize his new-found freedom.

When the chest of demons is stolen by the Shadow Demon, Vincent steers the gang toward Befuddle Manor before the crystal ball gives out. In their search for the chest, they are captured by the Queen of Ghouls.

While at a paranormal convention, the gang is chased by Reflector Spectre and his henchmen. It's up to the gang to capture the ghost and solve the mystery of the disappearance of a maid who was taken into the Spectre's mirror world by mistake.

Zomba, the host of the "Spine Tingler Movie," is one of the escaped demons who sweeps the gang into their TV, where they are trapped in an old Frankenstein movie.

Scooby's nerves are frazzled so the gang goes on a cruise. Unfortunately, their travel agent is one of the thirteen ghouls, and he sends the gang on a trip into the Bermuda Triangle.