Title rated 4.1 out of 5 stars, based on 40 ratings(40 ratings)
Book, 1968
Current format, Book, 1968, , Available .
Book, 1968
Current format, Book, 1968, , Available . Offered in 0 more formats
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.
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