All-Winners Comics #15 (1945)

The Sub-Mariner is visiting with his inventor friend Roy Winters who shows him his new boat engine. After the test, Roy tells Namor that he built the engine without any blue prints. Roy and Namor agree to meet at the Mill Street Pier that afternoon for further tests. As he arrives on the scene he sees a group of suspicious men fleeing from Roy's boat. When Namor attacks them they knock him out with a blackjack and flee the scene. When Namor revives and goes to Roy's boat, he finds Roy dead, apparently from a self inflicted gun shot wound to the head. Namor finds a suicide note that states that he killed himself due to the motor being a failure and that he's destroyed it. Checking, Namor finds that the engine has been taken from the scene. When the police arrive on the scene, they dismiss it as a genuine suicide, but Namor is not convinced and suspects foul play. Namor tells the officer on the scene that he is going to report the story to his newspaper friend Betty Dean. Unknown to Namor, one of the thugs involved in Roy's killing overhears this and reports back to his employer. With Namor being the only person who has seen the engine, the crooks boss begins planning a trap for the hero. They send a note to Betty Dean at the newspaper asking her to go to the Blue Circle Inn regarding a news scoop. Ever the newshound Betty rushes to the Inn which has been closed for many months. When she enters the building she is gassed and taken prisoner to use as bait for the Sub-Mariner. Meanwhile, Namor had come across the note sent to Betty and has come to the Blue Circle as well and is spying through the skylight. Namor smashes through and easily beats the crooks into submission. Questioning the kidnappers, Namor finds out that they do not know who their employer is. Looking around for clues, Namor finds a calendar that advertises the local boat speedway and realizes that the engine might be in one of the boats there. Looking around, Namor is attacked by guards which he easily subdues them and learns that the head launch has been put on a test run. There he finds Mr. White attempting to sell the engine to another business man. When Namor accuses him of killing Roy and stealing his engine, White denies it. Namor then decides to prove it by taking them back to Roy's lab to search for proof with the police. When Namor claims to have found blueprints, White breaks his cover and gasses the officer and Namor and attempts to escape. Namor revives quickly and chases after White who jumps off the George Washington Bridge. White then climbs into a boat and threatens to blow it up with TNT, but Namor easily stops him. Turning White over to the authorities, he tells the police that his committed the crime to try and save his failing business. Later Namor reveals that when he was in Roy's lab, he pretended to find a blue print for the engine to make White blow his cover.