With Mystery Inc. broken up, the gang decides to check out life after high school and spend a weekend at DARROW COLLEGE. But things don't go as planned when a creature called CHAR GAR GOTHAKON begins terrorizing the campus. Turns out this beast is a fictional character come to life. A creation of the author H.P. HATECRAFT who is a professor at the school.

Feeling left out of the group, Velma goes solo to investigate attacks by amphibious "Fish Freaks" in the area around an abandoned oil rig, only to find a friend of her own... in the form of a mermaid!