The Shore Road Mystery (Hardy Boys #6) by Franklin W. Dixon

When the Hardy Boys eagerly agree to assist their friend Jack Dodd and his father in locating a family treasure, the two young detectives are unaware of the baffling complications that will arise. Deadly road traps, aerial ambush, a spider man and a suspect who carries a menacing cane harass the young detectives as they seek the triple solution to this perplexing and exciting mystery.