The Sinister Signpost

In 'The Sinister Signpost', the Hardy Boys, Frank and Joe, encounter a mysterious road sign that seems to cause accidents. Their search for answers leads them to the Signpost Gang, a group using the signpost as a distraction for their criminal activities. The boys must overcome dangerous obstacles and unravel the gang's plot, in an adventure full of mystery, tension and excitement. Racing cars, mystery, and adventure combine to give Frank and Joe Hardy one of the most dangerous and intriguing cases of their careers. It starts when their father, Fenton Hardy, is engaged by an experimental race car and motor designer to investigate a series of mysterious accidents. Each of the drivers had seen a signpost marked DANGER shortly before the accident. The young detectives investigate, only to discover that the signposts have vanished. What happened to them, and what sinister purpose did they serve? 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.