It is the fifth of Columbia Pictures' eight The Whistler films produced in the 1940s, the first seven starring Dix.
Dix plays the film noir private eye which is set up to tip top perfection complete with the flashing neon sign working the urban evening outwith and casting a technogothic glow across the office.
As a theme, sanatorium noir has never been fully proposed despite their being some decent sanatorium cinema from the 1940s in particular. Mysterious Intruder (1946) is fun and loose, not always convincing, but yet features a strong noir cast, relative to the budget and production values.