The dominant matron of a wealthy southern family prevents her daughter Rachel (Karen Morley) from running off with the man (Robert Wilcox) she has secretly married. There's an argument; there's a struggle for a revolver; the girl's father is accidentally killed; the groom flees and the girl is stuck—to spend the next many years alone in the decaying mansion with her mother, her two bitter brothers, and a butler whose devotion to the mother runs dark and deep. So begins The Unknown—in a lengthy introductory scene narrated years later in ghostly tones by the finally deceased mother.
Jumping to the present day, we see Jim Bannon and Barton Yarborough arriving on the scene with another young woman—Jeff Donnell as Nita, the now grown daughter of the cruelly separated couple of the opening scene. Bannon and Yarborough are, of course, Jack Packard and Doc Long, back for a third and final appearance as the detectives from I Love a Mystery.
The mystery this time around involves strange baby cries from behind the walls, the unbalanced Rachel (played by a sufficiently disturbed Morley), a family crypt and house full of busy secret passages, and our detectives' efforts to present Nita as a legitimate heir to the place—efforts that are quickly expanded to include keeping her safe and sane.
The suspense develops nicely; the atmosphere crawls with sinister shadows and inscrutable, furtive glances and creepy noises; suspicion is cast cleverly over an assortment of possible villains.
Short and sweet, The Unknown is hardly nightmare-inducing, but it's certainly a fast-moving and entertaining little picture. –Call me a sucker, but I'll admit to goose bumps running up my spine in at least one scene.
