A mysterious weapon is destroying American U2s. The Seaview's mission is to find the weapon and destroy it. Captain Crane goes undercover. A night-club performer, who is also a resistance fighter, comes to Crane's aid. The Captain is soon captured and severely beaten. Meanwhile, on Seaview, Major Amadi demands asylum. To prove his sincere intentions, he promises to lead the sub to the powerful magnetic weapon responsible for taking out those U2s. Nelson suspects he wants to lead Seaview to a watery grave.
Elenco: Richard Basehart , David Hedison , Robert Duvall , Terry Becker , Del Monroe , Paul Trinka , Richard Bull , Robert Dowdell .