A young American couple, Peter and Joan Alison, are honeymooning in Hungary when they meet Dr. Vitus Werdegast, a psychiatrist who has recently been released from a prisoner-of-war camp after fifteen years. When their bus crashes in a storm, the trio takes refuge in the modernist mansion of Hjalmar Poelzig, a renowned architect. Werdegast reveals to Peter that Poelzig betrayed him during the war, leading to his imprisonment and the death of Werdegast's wife. Tension escalates as Poelzig offers hospitality while Werdegast's true motive for visiting becomes apparent - he seeks retribution and to reclaim his lost wife and daughter.

As the night unfolds, it becomes evident that there are sinister secrets within the house, and Poelzig is involved in a diabolical plot. The modernist mansion filled with eerie corridors and an ominous atmosphere sets the scene for a night filled with psychological horror and suspense. Werdegast, driven by revenge, must navigate the twisted mind games set up by Poelzig while protecting the unsuspecting couple from impending doom. Complex relationships of betrayal and vengeance come to a head, leading to a gripping confrontation where the true horrors lurking in the shadows are unveiled.