Sahara sandwich (1991)

Ryder is a psychiatrist who can flawlessly analyze his clients' problems, but is hopelessly alone in solving his own mental distress. One day, Sleuth, a detective, bursts into Ryder's office with the news that Ryder is suspected of murdering three women. Ryder is unaware of any wrongdoing. However, he has received a mysterious letter announcing a murder, and Lizzy, his secretary, has disappeared without a trace. The confessions of a new patient set Ryder thinking. A verbal cat-and-mouse game ensues between Ryder and Sleuth, but it raises more questions than it answers. If the murders have been committed, what is the motive? And if there is no motive, can there be a suspect? Or has everything been staged? Perhaps by Sleuth or Ryder himself?