Death at the Bar is a crime novel by Ngaio Marsh, the ninth to feature her series detective Chief Detective-Inspector Roderick Alleyn of Scotland Yard and published in 1940 by Collins (UK) and Little, Brown (USA).

The cast of suspects is completed by Decima Moore, a local farmer's daughter recently graduated from Oxford University, who has an understanding with Will Pomeroy, based on their shared left-wing views, and with whom Watchman is eager to rekindle a brief fling from the previous year.

Alleyn rapidly detects the usual welter of motives, and the case seems to revolve around an old fraud trial, in which Watchman successfully defended Lord Bryonie by suggesting he was the gullible pawn of Montague Thringle, who was convicted and given a severe prison sentence.

Before Alleyn can unmask Watchman's killer, in the face of considerable obstruction or outright hostility from the suspects, he only just contrives to save his assistant Inspector Fox from death by drinking cyanide-laced sherry from a bottle set aside for the two policemen.

Maurice Percy Ashley writing in The Times had strong praise for the plot and noted an improvement in style compared to her earlier novels, less sentimental.

Miss Marsh “presents us with a really clever problem in detection, the very thing to absorb our attention on snowbound, blacked-out evenings.”[1] Ralph Partridge in The New Statesman called it a competent story, as “All the characters are lively, all the suspects plausibly suspicious and the clue is scrupulously fair.”[2] Katherine Woods in The New York Times called it “a treasure” because of the rich characters, humor and setting, on top of the key aspect, a mystery to solve.

[3] Isaac Anderson in The New York Times Book Review liked the characterizations, and said “she knows how to employ humour without overplaying it.”[4] In her autobiography Black Beech And Honeydew,[5] Ngaio Marsh describes Marton Cottage, the home in the hills outside Christchurch (NZ) she shared with her widowed father, as "a masculine household... with the emphasis on my father's generation", who would gather there of an evening to play darts.