Mystery House is a perfunctory Warner Bros. programmer which coasts along on the appeal of its stars. When a prominent banker is murdered while on a hunting trip, the dead man's daughter, Gwen Kingery (Anne Nagel), calls in private eye Lance O'Leary (Dick Purcell) to investigate. No sooner has he started gathering clues than another murder is committed?and another?and another?.The culprit wants to cover up an embezzlement scheme, and there is certainly no shortage of suspects. Without revealing the ending, it can be noted that Mystery House offers at least one surprise when Lance O'Leary ends up falling in love not with Gwen Kingery but with wisecracking nurse Sarah Keate (Anne Sheridan). Sarah, in fact, is the leading character in the Mignon C. Eberhardt novel upon which Mystery House was based-except in the original, she's a middle-aged spinster rather than a Hollywood glamorpuss.