Mystery House staffers would perform in each half-hour drama, while others would provide sound effects, rewrite scripts and so on. But could this really succeed as a business model? Would people buy a mystery book if they already knew the ending? An interesting question, considering how little information there is available about the firm -- or if, in fact, it even existed.
Research into this query turned up an address for "Mystery House" at 70 Park Avenue in New York City, where a hotel now stands, and that the publishing firm ceased operation sometime after 1964. As for the broadcast history behind the series, the "shroud of mystery" remains intact. Newspaper archives report a series with that name as having been broadcast in 1929 over WGN in Chicago and apparently still on the air as late as 1951.
The show was broadcast in a variety of formats; sometimes as a weekly half-hour, sometimes as a five-day-a-week quarter-hour show. Mystery House has also been associated with appearances on WOR in New York; both WOR and WGN were flagship stations of the Mutual network at that time.