The robot's revenge

By Franklin W. Dixon

Subjects: Juvenile Mysteries, series:HardyBoys, Children: Grades 4-6, Mystery and detective stories, Juvenile Fiction / Action & Adventure, Juvenile Fiction, Mysteries, Espionage, & Detective Stories, collectionID:HBMS3, Children's 9-12 - Fiction - Mysteries / Detective

Description: The Hardy's invention, Roger the Lobber, an automatic tennis ball retrieval and return unit, has been stolen from the Teen Inventor's Club competition and then reappears without warning, transformed into a device of danger.