While The Clock Ticked by Franklin W. Dixon

Two teenage detectives are called to help a reclusive man who receives terrifying threats inside a supposedly secure room, even when it’s locked from the inside. As they follow cryptic clues around a cliffside mansion, they uncover secret passages, shadowy intruders, and a connection to an old crime. Racing against a ticking deadline and a hidden trap, they outwit the culprits, expose the method behind the impossible notes, and restore safety to their anxious client.

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