After police lieutenant Mike Travis supervises the removal of the corpse, he returns to headquarters to find a sailor, Frank Larkin, being booked for participating in a bar brawl.

In Washington, D.C., a navy commander informs Lt. Brad Chase, an intelligence officer, that the notes were part of a two-million-dollar shipment from the Federal Reserve Bank for wartime counter-intelligence activities in Japan.

After the commander orders Brad, a former Los Angeles crime reporter, to investigate, he returns to California where he meets his old friend Mike and his former rival Val, who senses a story in the offing.

Meanwhile, Swede Nelson, one of the two naval frogmen originally assigned to retrieve the sunken money, is aboard an offshore tuna boat, awaiting a signal from his partner Sam Marvin.

After killing his diving companion, Swede tried to retrieve the money on his own for several years until enlisting Marvin's backing and help in transporting the cash to Panama where a tuna boat picked it up and took it to California.

At Marvin's signal, Swede leads a team of three divers as they submerge to hide the money, encased in metal containers, in a cave underneath the sea.

Worried by the fact that some notes are now in circulation, Marvin discovers that Larkin and another member of the boat's crew helped themselves to the cash to cover gambling debts.