Baron Maderstrom, a passenger on a zeppelin, seeks safety in a rural estate in England. He delivers Lady Cranston the word of her brother, a German prisoner of war whose freedom he pledges to arrange. Lady Cranston, on the verge of declaring him a spy, is convinced by her brother's betrothed, Helen Fairclough, to harbour the Baron and pass him off as an English houseguest going by the name Hamar Lessingham. Phillipa Cranston's husband eventually joins these three key characters on stage. Sir Richard Cranston, formerly a loyal spouse, is now considered by his wife as a slacker who is not contributing to the war effort.
