Billy is a staff member at museum who leads a tour into the museum's star attraction, an immaculately preserved giant squid, only to find that the massive tank has somehow vanished from the locked room.

This sends him off on adventures through London where he learns of its role as a world nexus for all manners of magic and cult activity while also trying to prevent the stolen squid from being used to spark a global apocalypse.

Not terribly deep, but an entertaining light romp.