The Green Mask, alias Walter Green, is a U.S. mystery man and action-hero based in New York City. His abilities included detective skills and the art of disguise. The Green Mask wore a blue costume with a brown leather belt, blue gloves and boots, a blue cape with a red lining, and a green cowl. 1)
Becoming the Green Mask under unknown circumstances, Green quickly made a reputation for himself as a crime-fighter but often played the part of a masked criminal in order to infiltrate criminal gangs, and he was thought to be a criminal by the police. He exposed an insurance fraud ring that collected insurance money for people it murdered, which was secretly headed by a politician named Cyrus Boomer. 2) The Green Mask put an end to the murders in Chinatown committed by men working for the arch-criminal San Sin. 3) The Green Mask exposed a respected citizen named J.J. Faken, who adopted boys from the State Reformatory and taught them to be thieves for him. 4) The Green Mask defeated the master criminal scientist Nicoli, who had invented a small paralyzing gun he used for several major robberies (and which the Green Mask added to his arsenal), and rescued the Police Commissioner's daughter, June. 5) He prevented Janette Lovingston, who had murdered her brothers David and Leon for inheritance money, from killing the last brother Stanley and his daughter Estelle in Africa. 6) The Green Mask stopped a Hindu cult that had robbed and murdered anyone possessing the sacred Taj Lamah jewels that had come from a sacred jewel-encrusted skull. 7)
In June, 1940, after Senator Shelby was assassinated by a criminal organization called the Grim Circle, his son Michael Shelby gained super-powers through exposure to a vita-ray machine. Green approached Shelby and asked him to carry on the identity of the Green Mask while Green left to fight the Axis in World War II. 8)