Dixon, Franklin W. author New York Grosset & Dunlap 1996 eng 180 p. ill. In one of the most dangerous and intriguing cases of their careers, Frank and Joe Hardy help their father investigate a series of mysterious car accidents. Each of the drivers had seen a signpost marked DANGER shortly before his accident. The young detectives investigate, only to discover that the signposts have vanished. The attempted theft of a secret experimental motor and the kidnapping of a famous race horse are part of this thrilling case, which proves to be as sinister as the signposts themselves. [Fic] 9780448089157 000031/00003159.jpg 000031/00003159.jpg BR-BrIDEA 118602