President Henry McNeil has fallen and seriously injured his head. That imperils an upcoming peace conference; even a whiff of the president's incapacity may doom it, as he is the one man who can hold it together. Everything depends on a delicate operation to relieve the swelling in his brain. To keep that operation a secret, the Navy co-opts the Seaview. But enemies of the conference have learned of the president's ill health, and manage to smuggle an agent aboard Seaview with orders to kill McNeil!
—CommanderBalok