Crook O'Lune is a 1953 detective novel by E. C. R. Lorac, the pen name of the British writer Edith Caroline Rivett.

[1][2] It is the thirty eighth in her long-running series featuring Chief Inspector MacDonald of Scotland Yard, one of the more orthodox detectives of the Golden Age of Detective Fiction.

[3] It was published in the United States by Doubleday under the alternative title of Shepherd's Crook.

While visiting friends in Lancashire, and looking for a property to settle down in when he retires from Scotland Yard, MacDonald agrees to lend his assistance to investigate some sheep-stealing.

Before long he is drawn into a case involving arson, blackmail and attempted murder.