What could have driven the successful and respectable dentist Morley to commit suicide? He had neither mental illness, nor a lack of money, nor a tragic love affair. The famous detective Hercule Poirot, a longtime client of his, doesn't believe the suicide theory. While investigating the case, the Belgian meets and talks with Dr. Morley's old patients, associates, and friends. As a result, Poirot becomes firmly convinced that the dentist had long been plotted to be killed. And not just him...