Nickel Comics #3 (1940)

Bulletman the Phantom Foe of Crime has a "Showdown with Blackmask," who is after a diamond shipment. He's also trying to kill Bulletman, which he attempts with: 1/ a boobytrapped armored truck with poison gas followed up by a traditional trip to the bottom of the river with feet in a bushel of concrete, and later, 2/ his own boobytrapped radio-HQ with poison gas followed up by high explosives, and later still, 3/ his own other boobytrapped radio-HQ, in a steel room with hydrochloric acid covering the floor and an electrified ceiling. After escaping trap #1, Bulletman straight-up carjacks a coupe, and drives it, with big hunks of cement on his booted feet, then rips the fire-escape off one building and uses it to climb another, and foils the diamond-shipment-thieves's rooftop getaway by wrecking their autogyro. After escaping from trap #2 and rescuing it from a big explosion, Bulletman carries Blackmask's cat around for an extraordinary length of time, possibly hoping to use it later, in identifying Blackmask. Bulletman follows-up a squealer's tip by using a directional antenna and testing various wavelengths, while speeding thru the city, to locate Blackmask's secret radio station. Blackmask escapes from his own HQ via a chute accessed thru a man-sized circular porthole in one wall. Blackmask's submarine getaway is foiled by Bulletman dumping 3 truckloads of cement into the river; he turns out to be newspaper publisher Stephen Doone.