Baron Schluss was a spy for the Nazis during World War II. By the spring of 1944 he had relocated to the United States and set up operations with a group of spies that worked out of a New York aquarium that overlooked the harbor. He and his minions planned to smuggle explosives from a U-Boat out at sea into the aquarium to eventually be used in acts of sabotage.
Unfortunately for them, their plot was foiled when the Sub-Mariner took at nap in one of the aquariums fish tanks after being stood up on a date by Betty Dean. When Namor awoke, he overheard the plot and confronted the spies. An attempt by Schluss and his men to destroy Namor by using a squid and a tank full of sharks failed, but slowed the hero down enough to allow them to head toward the U-Boat by motorboat. The Sub-Mariner caught up to them and caused their boat to crash into a buoy, killing all aboard in an explosion. Namor then destroyed the enemy sub, putting an end to the sabotage plot before it could begin.