Sergeant Beck drives out to the river and finds Detective Lewis peering into the water. He drives Lewis back to the Police Station for a meeting with Chief Superintendent Laidlow. Everybody asks Lewis why he didn't come to the dance the night before. Laidlow is furious with Lewis, a recent recruit who has made no friends despite his intelligence and good record of arrests. Laidlow has to decide whether to let him stay or not and banishes him from his sight until he makes up his mind. Lewis is assigned to keep an eye on James Cummins, who is suspected of being responsible for the theft of three trucks loaded with brandy.

When Cummins refuses to let him into his house, Lewis returns to his car and waits. Cummins eventually has his bodyguard-cum-butler Arthur bring Lewis to the house. Lewis tells Cummins that the brandy theft is most likely his work or that of his associate, Blond. A night watchman was very seriously hurt in the theft and Lewis won't give up until the crime is solved. The next day, at Laidlow's insistence, Lewis goes to Brighton and follows Blond, who is furious that the CID is tailing him. He argues with Cummins over the telephone about the theft of the brandy. Lewis returns to wait outside Cummins' house.

Cummins applies pressure on a councilman to get Lewis re-assigned. Laidlow visits Lewis and, impressed by his determination to get the job done and gain the respect of his colleagues, lets him continue. When Lewis sees a woman being paid by Cummins, he follows her to an empty house. There he is beaten unconscious by Arthur, who also photographs him in compromising positions with the woman. Lewis returns to Cummins' house. The girl in the photos is Blond's latest girlfriend, and she will deposit money in Lewis' account to make it appear that he is corrupt if he doesn't drop the case. Lewis realises that Blond has some hold over Cummins, who admits that he got Blond's daughter pregnant and is now refusing to take responsibility for it. Cummins tells Lewis where the brandy will be delivered in Brighton.

The next day Lewis tells Cummins that he had Blond arrested and that the trucks, with no one to accept delivery in Brighton, are now heading here. Cummins, defeated, begs him to leave, but Lewis stays in his car, waiting.