The Strega-Borgia children accidentally create 500 clones of themselves at the same time that the roof on their Scottish castle falls in, attracting evil contractors who want their home.

Danger continues to find the members of the eccentric Strega-Borgia family at their Scottish castle, this time in the form of a butler who wants to blow up a nearby corporation and a demon who seeks the all-powerful Chronostone.

As usual, the Strega-Borgia family can't seem to get a break:
They've just welcomed a newborn boy Strega-Borgia into the world, but before they can give him a name, he's snatched and replaced with a demon baby. Mrs. McLachlan, the super-efficient (and supernatural) nanny is back, safe and sound—but so is the demon Isagoth, and he hasn't forgotten what he wants from the Strega-Borgias. And evil Uncle Lucifer has resurfaced, but this time...