During his run on radio, Ellery Queen bounced from network to network starting on June 18, 1939 on CBS Radio. He stayed there until September 22, 1940. The show was revived for a run on NBC Radio from 1942 to 1944, then back to CBS until 1947, then back to NBC for a year until finally ending up on ABC Radio from 1947 to 1948.
"The Vanishing Magician" was Ellery's 150th radio adventure, airing on the East Coast on November 4, 1943 and on the West Coast two days later on November 6. Sydney Smith played Ellery, Santos Ortega played Inspector Queen, Ted de Corsia played Sergeant Velie, and Marian Shockly returned from a two-month hiatus to play Ellery's secretary, Nikki Porter. (During those two months, Nikki was played by Shockley's friend Helen Lewis; Lewis was an expert mimic and voiced Shockly so well that most did not know it was a "different" Nikki.) Ernest Chappell was the announcer. and Charles Paul provided the organ music. The episode was produced by Bruce Kammon and directed by Bob Steel from a script by "Ellery Queen."
For those interested in minutia, the sponsor was Bromo Seltzer.
This episode was a repeat of "The Disappearing Magician," which aired on September 15, 1940, when Hugh Marlowe was playing Ellery and Bert Parks served as announcer.
One gimmick to The Adventures of Ellery Queen had the action stop near the end and had two special guests try to solve the mystery. The guests for the East Coast version (heard below) were
Sonia Bigman (radio editor for Time magazine) and Edward Pawley (the star of radio's Big Town); West Coast guests were radio actress Linda Watkins and B. Pemberton (of whom I know nothing).
Match wits with Ellery Queen as you meet a has-been vaudevillian who vows to disappear from a house for $25,000.