Set during World War II, Susan and Gwennie are two girls bound for London. There, Gwennie is to meet her father, a very prominent politician and Susan is to visit her boyfriend, Arthur, who wants to join the army. They come into contact with Gwennie's father who makes it possible for Arthur and the others to join the army. When they are posted to King Arthur country, Arthur is given an 'Excalibur' as a practical joke, but genuinely believes he is in possession of the legendary sword and therefore believes himself to be invincible. But who will have the last laugh?