When Herbie and Violet's arch-enemy Sebastian Eels turns up in Eerie-on-Sea, seemingly back from the dead, it can only spell bad news.

The town may welcome his entrepreneurial scheme to resurrect Festergrimm's Waxworks, a dusty and defunct old gallery of spooky characters from Eerie legend, but Herbie and Violet are suspicious of his motives. And when they learn the legend of Ludo Festergrimm the clockmaker, creator of a vast mechanical robot that wrought havoc in the wrong hands, they KNOW they're on the right track.

But how can they get the residents of Eerie-on-Sea to believe them?