The Shore Road Mystery by Franklin W. Dixon

Two teenage brothers investigate a rash of car thefts along a coastal road near their hometown, following a trail of suspicious clues, decoy license plates, and shadowy suspects. Battling ambushes and close calls, they uncover a clever ring of thieves who hide stolen vehicles in secret seaside caves. With help from their friends and their own quick thinking, they piece together the scheme, recover the missing cars, and bring the criminals to justice.

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