Dr. Quest and the team are on their way to visit Prof. Erickson and his latest invention. But there are sinister forces at play who want to get the formula to the latest invention, and one of its agents are pretending to be a gargoyle. Jonny started noticing strange things much sooner, first the submarine periscope, then noticed the gargoyle moved, but noone believed him and thought it's just boy's imagination after all the talk about ghosts in the spooky castle they are visiting.