Operation Titanic (Nancy Drew/Hardy Boys)

Operation Titanic is a Nancy Drew and Hardy Boys Supermystery crossover novel. It was published in 1998.

Plot summary
Nancy and Bess arrive on a freighter that is on a mission: to raise the Titanic from the ocean depths! They then discover a plot threatening the ship that involves a CIA double agent.

Meanwhile, the Hardy Boys go undercover as journalists; they arrive on the ship by helicopter, planning to undercover a terrorist in disguise and frustrate his evil plans.