A young woman named Marie Morgan (Ginger Rogers) arrives at night at a presumably vacant old house, and is quickly murdered by person unknown. A private detective named Phil Winston (Lyle Talbot) proceeds to investigate, with the help of an annoyingly grumpy cop and his bumbling sidekick.
As the whodunit plot moves along, various characters reveal the backstory, involving a rich old man who invites thirteen guests to a dinner party at which time he will announce who inherits his estate; problem is the old man dies at the dinner without revealing his secret.
The main problem is a script that is so convoluted that it's almost impossible to figure out the puzzle's solution. Once known, the solution is not remotely believable, and there are significant plot holes. Still, there's enough suspense to keep the viewer watching despite a substandard script. Dialogue comes across as stiff and stilted at times but there are a few good lines.
Before the killer's identity is known, this person appears in a few scenes wearing bizarre garb that covers his/her body completely; the costume makes the person look a little like spider man. The film's prod design is cheap looking. Most of the action takes place indoors and mostly at night.
Casting is acceptable except for the presence of Lyle Talbot who just doesn't have the mystery persona of someone like Sidney Toler or Warner Oland. Indeed, if the film had been made as a Charlie Chan thriller, I think it would have been better.
For all its faults, "The Thirteenth Guest" is worth watching once, owing to adequate suspense in a spooky old house with hidden rooms and a masked killer. Overall, it's an average whodunit for the era in which it was made.