Double Star by Robert A. Heinlein

Another one of the great ones. An out-of-work actor is recruited to fill in for a kidnapped politician. When he realizes what the job is, he believes that he has been set up to take the bullet in an anticipated assassination attempt. Unfortunately for Lawrence Smith, the self-styled Lorenzo Smythe, it wasn't nearly so simple.

Heinlein's fifties paternalistic attitude toward women is fully apparent. There is only one female character in the story, the politician's faithful secretary, and she is quite stereotypical - buxom, adoring, jealous. Still, good fun.