With heart problems, former military pilot George Jones is now confined to bed in his suburban home. His primary caregiver is his loving wife, Ellen Jones, and he being under the medical care of his longtime friend Dr. Ranney Grahame, the two who have known each other since college. It is through Ranney that George and Ellen first met when Ranney was a military physician, who, unknown to her, was attracted to her, she only seeing him as a friend, something that he accepted. Ellen learns that George believes that she and Ranney are now in love with each other and are having an affair, that belief which Ellen attributes solely to George's delirium a result of his health problems exacerbated by the current heatwave. What Ellen does not know is that George further believes she and Ranney are trying to kill him so that they can be together, and that he additionally has taken measures to punish her if she does try to kill him, he ultimately planning to kill her to beat her to the punch. If she does discover George's thoughts concerning these latter items, it may be too late for her to save herself.
—Huggo