The Vanishing Shadow (1934)

An electrical engineer, Stanley Stanfield , brings his newest invention to the famous electrical wizard, Carl Van Dorn --- a vest-like apparatus that enables the wearer to vanish, leaving only a shadow. Van Dorn is vastly impressed and, with the aid of the machine, the pair set out to bring about the downfall of power-crazed, money-mad Wade Barnett and his crony Dorgan, whose political-group activities, through a vicious smear campaign, had hounded Stanfield's father to death. Stanfield's efforts are complicated by the fact that his girlfriend, known to him as Gloria Grant is really Barnett's daughter, who has rejected her father and goes by an alias.