It begins with a conference with Bishop of Bedford, Soper (played wonderfully by Louis Jouvet), as the speaker. They are against crime novels written by the mysterious Felix Chapel, which is popular at that time. On the background there is a banner saying "Detective novel readers are future murderers". What Soper and others don't know, is that the mysterious Chapel is Soper's own cousin, the botanist Irwin Molyneux, who writes crime novels on his wife's suggestion for an extra income. In the conference, a notorious murderer William Kramps also attends. Kramps swears to kill Chapel because his books have inspired him to commit murders and he blames Chapel for that. [Later we find that Molyneux gets his inspiration from their maid Eva who hears the stories from the milkman, who delivers 4 bottles of milk every day for free because he wants to see Eva. I wonder why not only 1 bottle. Furthermore, it seems that none drinks the milk.]
After the conference, which ends bad because the police run after Kramps, Soper says to Molyneux that he will dine at his place. At the same time, Molyneux's cook and valet left. Molyneux's wife, Margaret, has to take over the cook's place, but as it is a shame for someone at her social status, they tells Soper that she has gone out to visit friends. Soper doesn't believe it and reports to the police that Molyneux has killed his wife.
The more it's going, the situation is getting more uncontrollable. I've hardly seen so many twists in one movie. Molyneux and his wife have to flee the house which is ransacked by the police who is looking for the body. Chapel has to come out for if he writes articles about the murder, the paper will pay him. In the end, Soper finds himself as the main suspect of the murder and the public are eager to hang him, ignoring Margaret who claims she is still alive. Margaret is accused of murdering her own husband, as Molyneux 'has to die' so that Chapel can gets the inheritance from their aunt - who is sick of the family (maybe one of them killed her dog Canada) and decides to leave her money to Chapel. Then arrives Kramps, who has fallen in love with Margaret (it's a hilarious scene when Kramps asks the Chinese hotel owner to bring him flowers. The hotel owner's man hit every passing man who has a flower and take it, to fill the vase.), to save the day.