Moving back to the radio-buoys in the river, Doc and aides (along with Rapid Pace and Hugh McCoy) set out in the "Helldiver" (Doc's submarine). They follow a trail of hidden buoys out into the Atlantic where they are attacked by another submarine (the buoys are intended to guide the villains' submarine down the river to an abandoned sewer that connects to the Indian's Head Club). They are eventually boarded and Doc Savage is apparently killed (this is a common event in Doc Savage stories). The rest are taken in the villains' submarine to their base in an almost derelict rum row ship. Doc, hanging on to the side of the submarine, sneaks aboard the ship, rescues everyone, recovers a lot of stolen goods and escapes in a lifeboat. A fire he started as a diversion causes an explosion (speculated to be either from the fuel tanks or a stockpile of explosives) and the ship sinks as they leave.