Murder Must Advertise is a 1933 mystery novel by Dorothy L. Sayers, the eighth in her series featuring Lord Peter Wimsey. Most of the action of the novel takes place in an advertising agency, a setting with which Sayers was familiar as she had herself worked as an advertising copywriter until 1931. Plot Death Bredon arrives at Pym's Publicity Ltd, an advertising agency, to take up the post of junior copywriter. He is assigned the room of his predecessor Victor Dean, who has died in a fall down the office's iron spiral staircase. The doctor states that death was caused either by a broken neck, due to his landing on his head at the bottom of the stair, or by a wound of the right temple. The death appears suspicious, as the victim apparently made no attempt to save himself as he fell. In Dean's desk Bredon discovers a part-completed letter to the firm's proprietor, Mr Pym, telling him that something 'undesirable' had been going on in the office. Bredon befriends Pamela Dean, Victor's sister, so that she can get him into a cocaine-fuelled fancy-dress party hosted by Dian de Momerie, a socialite with whom Dean had been associating. Disguised as Harlequin, Bredon attracts the attention of de Momerie and later meets her several times, always in disguise. His presence annoys de Momerie's companion Major Tod Milligan who is supplying her with drugs. It is revealed that Death Bredon is in fact Lord Peter Wimsey who has been brought in by Pym to investigate Dean's death. Various clues turn up: a catapult belonging to 'Ginger' Joe, the office boy; a carved stone scarab belonging to Dean; and £50 in banknotes found in the desk of Mr Tallboy, group manager. After having a drink in a Covent Garden pub, newspaper reporter Hector Puncheon discovers that someone has slipped cocaine into his coat pocket. Chief Inspector Charles Parker, Wimsey's brother-in-law, suspects that Puncheon has stumbled on Milligan's drugs gang, but finds no further suspicious activity there. It appears that the cocaine is being distributed from a different pub each week. Puncheon spots a man from the pub who is behaving suspiciously, and who almost immediately falls in front of a train and is killed. Searching the man's flat, Wimsey and Parker discover a phone book with the names of many pubs ticked off, including the one in Covent Garden. Wimsey realises what