BATMAN (1940) #394

Batman and Katia track down the Dark Rider, who seeks to pollute Gotham’s water supply with plutonium. In Gotham, Batman and Katia (the operative he met in Moscow) tracked down the Dark Rider and his statue. The Russian zealot was not planning a bomb, but to pollute Gotham’s water supply with the plutonium. Batman and Robin were able to stop him in time.