Flood Tide by Clive Cussler

NUMA director Dirk Pitt is drawn into a high-stakes marine mystery after a string of deadly incidents at sea uncovers a ruthless conspiracy: a hunt for lost treasure and dangerous undersea technology being exploited by a powerful adversary. Racing against time and tides, Pitt and his team undertake daring salvage missions, face betrayals and ocean-borne combat, and battle corporate greed and hidden agendas as they try to prevent a scheme that could wreak havoc on coastlines and global power.

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