Adapted from Clarence Budington Kelland's novel, a numbers cruncher takes over a movie studio to prove it can make a profit.
Businessman Atterbury Dodd (Leslie Howard) tells board chairman Grandpa Pennypacker (Tully Marshall) he is selling Collosal Pictures to Ivor Nassau (C. Henry Gordon) for half its worth. So Pennypacker sends Atterbury to Hollywood to prove it. Producer Douglas Quintain (Humphrey Bogart) gave Thelma Cheri (Marla Shelton) a contract because he loves her; but director Koslovski (Alan Mowbray) complains that she is his fiancé. In a cab Atterbury meets stand-in Lester Plum (Joan Blondell). Atterbury's room costs Colossal a $100 a day. He returns Lester's shoe to a boardinghouse and rents a room next to hers.
At the Colossal studio Quintain shows Atterbury the business and says that Nassau would close it down. Atterbury watches a blizzard scene as Thelma replaces stand-in Lester. Atterbury questions costs, and Lester gets him to make her his secretary. Lester tries to get Atterbury to stop work and go out. In his office he asks her to dance and marks her steps; but Atterbury goes out with Thelma. Nassau tells him he has much to learn. Atterbury sees that Koslovski has Colossal property, and Koslovski socks him. Atterbury finds Lester crying. She treats his face and shows him jujitsu. Atterbury holds her close and throws her down.
Atterbury watches "Sex and Satan" with Quintain, Thelma, Koslovski, and Lester, who says it left her numb. Koslovski and Thelma say Quintain was drunk while making the picture. Quintain quits, leaving Atterbury in charge. While Quintain packs, Thelma says she hawked her soul. Lester and Atterbury read cards from a preview. Atterbury says he will sell Colossal, but Lester says thousands will lose their jobs; she says only Quintain could help. Atterbury finds Quintain drunk protesting a cafe. In a cab Atterbury persuades Quintain to fix the picture; but Atterbury has to cancel Thelma's contract by involving her in a scandal. Atterbury goes out with Thelma until she is drunk. Lester reads the newspaper and cries. On the phone Pennypacker gets Nassau to buy Colossal. Atterbury fires Thelma for moral turpitude; but he gets a call from Pennypacker that he is fired and tells Lester.
Nassau offers Atterbury a job for $75,000 a year, but Atterbury sees unemployed workers. Quintain shows Thelma he has replaced her with a gorilla. Atterbury tells Quintain that Colossal is sold; but Quintain asks for two days. Atterbury and Quintain agree to risk prison to help the workers. Atterbury tries to stop the workers from leaving, closes the gate, and begs them to work 48 hours. Atterbury accuses Nassau of conspiracy, and the workers throw Nassau over the wall. Atterbury proposes to Lester, kisses her, and calls Quintain that they are in business.
This satire of the movie-making business shows a man believing only in math transformed by the love of a former child star while he is trying to clean up a corrupt studio system.