Wonder Man (1945)
Timid librarian Edwin Dingle has an extroverted twin brother, nightclub entertainer Buzzy Bellew. When Buzzy witnesses a gangland shooting, he himself is rubbed out by mob boss Ten-Grand Jackson. Before long, Edwin is visited by Buzzy's ghost, who persuades his bookish brother to help bring Jackson to justice. For the rest of the film, poor Edwin is possessed by his brother's sportive spirit, causing no end of confusion for Edwin's demure lady friend Ellen Shanley and Buzzy's more outgoing girlfriend, dancer Midge Mallon.