Based on Upton Sinclair's novel, two families suffer from alcoholism and Prohibition.
In the south "Persimmon" (Dorothy Jordan) tries to help her father Roger Chilcote (Lewis Stone) stop drinking; but he goes off drinking, gambling, and overdrawing bank accounts until the family fortune is reduced; then he commits suicide. When a group of men toast his spirit, Persimmon criticizes liquor and throws them out. In New York Pow Tarleton (Walter Huston) speaks for Wilson's re-election, drinks, and then hits his son Kip (Robert Young). Young novelist Roger Chilcote, Jr. (Neil Hamilton) visits the Tarleton's hotel. Wilson's victory is celebrated; but soon Jerry (Wallace Ford) goes off to the war. Roger though believes that war has no "right side." The movement for the Food Control Act would ban making alcohol out of grain during the war, and the 18th amendment would prohibit drinking alcohol.
When Persimmon arrives to visit her brother Roger, Pow lets her go to his room. Kip tries to throw her out but then apologizes. Roger comes in drunk with Jerry. They discover Pow stole his liquor and replaced it with water. On June 29, 1919 people stow away as much liquor as they can and then celebrate until midnight, as Prohibition goes into effect. Kip dances with Persimmon but is snubbed by her society friends. Pow buys alcohol from a back-room still. His wife catches him and breaks the bottle; in a fight he kills her, and he is sentenced to life in prison. Kip forgives him and tearfully tells the renters he is closing the hotel. Persimmon wants to help him fight bootleggers. Doleshal (John Miljan) assigns Kip to work with Abe (Jimmy Durante) in collecting evidence. Kip chokes on his first drink, and they are thrown out of a place that serves drinks. A man offers Kip a bribe, but he refuses it. Roger visits Persimmon and Kip, criticizing Kip's job. Persimmon tells Kip she is pregnant; they are happy.
Bootleggers in New York plan an association, intending to pay off some and strong-arm others. Abe disguised in a beard raids a nightclub. Men smash the bottles, and Kip arrests Roger and Eileen (Myrna Loy). After Roger buys some "bonded" liquor, we see how a factory puts on phony labels. Roger passes out. When Eileen arouses him, he discovers he is blind. The eye doctor tells him, Persimmon, and Kip that since Prohibition he has seen hundreds of these cases, because the government puts a chemical in alcohol to make it undrinkable, and some bootleggers don't remove it. Doleshal orders Kip to arrest those who sold it. The man who tried to bribe Kip now warns him. Persimmon goes to the hospital to have her baby, and Kip is kidnapped on the street. Abe tails them. Three men tie up Kip to drag him, but Abe shoots one man and rescues Kip. Abe is shot and tells Kip to get out before dying. Persimmon has their baby, and Kip hopes that somehow this liquor problem will be figured out.
This story explores the problems that led to Prohibition and those of Prohibition itself. Although Persimmon and Kip do not drink, they are drawn into the struggle because of their family tragedies. The attempted solution of Prohibition is seen as aggravating a health concern into an epidemic of crime and corruption.