When Lord Basil Epping receives a telegram from his old flame, Edith Fitzbadden, notifying him that she and her nervous brother Percy are coming to visit, Epping's business partner, Dennis Lindsey, hopes that Percy will infuse their business with working capital. Epping decides to go hunting rather than meet his guests, however, and instructs Dennis to entertain the Fitzbaddens at his country house. When Dennis' snobby aunt Della warns him to keep his hot-tempered wife Carmelita away from the Fitzbaddens, Dennis takes her advice and drives to the country with Della as his hostess. They are met by Bascombe, the "real estate agent," who informs them that the servants have deserted. In reality, Bascombe is the leader of a band of gangsters who are making nitroglycerin in Lord Epping's basement. After Della calls home to instruct her huband Matt to pick up the Fitzbaddens, Matt and Carmelita pretend to be Epping's servants, Hubble and Maria, and deliver the Fitzbaddens to the country house. Upon discovering that their host is away on a hunting trip, the Fitzbaddens decide to leave until Carmelita convinces Matt to impersonate Lord Epping. Meanwhile, the real Lord Epping returns to New York and decides to join the Fitzbaddens in the country. Back at the country house, Edith flirts with Matt, posing as Epping, while Percy challenges him to a high-stakes poker game. Matt leaves the card table just as the real Epping arrives and takes his place at the table. After Epping excuses himself, Matt, as Epping, returns to the table, and Percy decides to cash in his chips. When the poker stake, which has been stolen by one of the gangsters, is discovered missing, the Fitzbaddens insist upon searching the servants, and Matt quickly hides his Lord Epping hairpiece and reappears as Hubble. After Edith searches him, Matt discovers that his hairpiece has been stolen by a dog, and he and Carmelita pretend to be cats to lure the dog from its hiding place. Shocked by the servants' caterwauling, Percy and Edith demand to see Lord Epping, so Matt dons his wig. Della watches as Matt disguises himself as Epping, and when the real Epping comes downstairs, she thinks that he is Matt and insults him. Meanwhile, Bascombe, who has been summoned by Edith to investigate the stolen money, appears and sparks an argument between Epping and Percy over Epping's ancestors, and Percy announces that he plans to leave in the morning. That evening, Epping, dressed in his nightshirt, is accosted by Della who, thinking that he is Matt, orders him to take off his "outfit" and accuses him of being crazy. Della's outburst is witnessed by the increasingly incredulous Fitzbaddens. Plotting to scare the visitors from the house, one of the gangsters dresses in armor and clanks through the hallways, driving Carmelita and Matt to visit their spouses' bedrooms and incensing the Fitzbaddens, who still believe that the two are servants. Later, Dennis tells Matt about Epping's argument with Percy, and Matt, posing as Epping, apologizes to Percy and convinces him to sign the business contract. After signing the contract, Percy meets the real Epping, who orders him out of the house. In response, Percy declares that he is leaving before he "blows up," and at that moment, the nitroglycerin in the basement explodes, prompting Matt to observe that Percy is a man of his word.