WBN, America's fourth radio network, is about to launch in 1939. Penny Henderson, the owner's secretary, must deal with an unhappy sponsor, an overbearing boss, and a soon-to-be ex-husband who desperately wants her back. As the broadcast begins, a mysterious voice interrupts it, and members of the cast mysteriously die. As the police pursue him through the halls of WBN, it's up to her husband Roger to figure out whodunit.