In the fall of 1933, NBC writer Wyllis Cooper conceived the idea of a midnight mystery serial to catch the attention of the listeners at the witching hour. The idea was to offer listeners a dramatic program late at night, at a time when the competition was mostly airing music. At some point, the serial concept was dropped in favor of an anthology format emphasizing crime thrillers and the supernatural. The first series of shows (each 15 minutes long) ran on a local NBC station, WENR, at midnight Wednesdays, starting in January 1934. By April, the series proved successful enough to expand to a half hour. In January 1935, the show was discontinued in order to ease Cooper's workload (he was then writing scripts for the network's prestigious Immortal Dramas program), but was brought back by huge popular demand a few weeks later. After a successful tryout in New York City, the series was picked up by NBC in April 1935 and broadcast nationally, usually late at night and always on Wednesdays. Cooper stayed on the program until June 1936, when another Chicago writer, Arch Oboler, took over. By the time Cooper left, the series had inspired about 600 fan clubs.