In New Mexico, the widow and former teacher Katherine Samuel reluctantly hires the lonely mathematician and genius Archie Landrum to be her gardener and soon they become good friends. When her estranged daughter Lucille "Lucy" Samuel, who left the college to become a television star in New York, decides to spend a couple of days with her mother, Archie becomes obsessed for her. Lucy and her mother reconciled to each other and Lucy decides to quit her career to stay with Katherine. However the obsessive Archie guns Lucy down witnessed by Katherine and is arrested. The ambitious local lawyer Joseph Smith prepares to defend him seeking the spotlights. Meanwhile, Archie mocks the Mexican Officer Gilbert Tellez, who is the guardian of his cell, and plans to seem a lunatic to escape from the death penalty. Will justice work?