Cody Chang's San Francisco store could be considered creepy-Skin & Bones sells animal skulls, fish skeletons, reptile skins, and more. Business is booming, but when Frank and Joe visit the shop, Cody tells them he's been the victim of a string of burglaries, computer thefts, and treatening messages.

The Hardy's immediately pinpoint a suspect-a criminal who was once caught in a sting by Cody's father, a policeman. Now there's danger everywhere for Frank and Joe-from a cable car accident to the dense redwood forests of Muir Woods to the foggy, ice-cold waters off Alcatraz. The brothers are running hard and thinking fast-up against a smart, desperate enemy ready to skin them alive!