What is Knock on Wood about?
Ventriloquist Jerry Morgan has to see another love affair fail. The reason: when the relationship reaches the point when it is time to discuss marriage, his doll Clarence becomes mean and jealous. His fiancée Audrey leaves him and Jerry smashes his two dolls, Clarence and Terrence. Morgan's doll maker Papinek is a member of a spy ring who has stolen secret plans to the top secret Lafayette airplane. Since Morgan is leaving for Zurich the same night, Papinek decides to use Morgan's dolls as a mailbox and hides the secret plans in the heads of the dolls. Another secret spy ring also wants to get their hands on Jerry's luggage and they *also* follow him. Eventually, Jerry is chased by both these organizations as well as the police, who suspects him of murder.