Eight people arrive on an isolated island off the Devon coast of England. Each appears to have an invitation tailored to his or her personal circumstances, such as an offer of employment or an unexpected late summer holiday. They are met by the butler and cook (who have never met their employer), making a total of ten people known to be on the island. While awaiting their hosts, they find a framed copy of the nursery rhyme "Ten Little Soldiers" ("Niggers" or "Indians" in respective earlier editions) hanging on the wall, and notice ten figurines on the dining room table, as well as discussing other oddities about the house and their visit. The butler plays a gramophone (or "phonograph") record while they are talking, as he had been instructed to do; unexpectedly the recording contains a voice that describes each visitor in turn and accuses each of having committed murder but evading justice, and asks if any of "the accused" wishes to give a defense. All are shocked and in the aftermath one of the guests (Anthony Marston) has a drink to help with the shock; however, his drink was poisoned with potassium cyanide and he chokes and dies. Subsequently the guests notice one of the ten figurines is now broken, and the nursery rhyme appears to reflect the manner of death ("One choked his little self and then there were nine").
- Current published version of the rhyme
Ten little Soldier Boys went out to dine; One choked his little self and then there were nine. Nine little Soldier Boys sat up very late; One overslept himself and then there were eight. Eight little Soldier Boys travelling in Devon; One said he'd stay there and then there were seven. Seven little Soldier Boys chopping up sticks; One chopped himself in halves and then there were six. Six little Soldier Boys playing with a hive; A bumblebee stung one and then there were five. Five little Soldier Boys going in for law; One got in Chancery and then there were four. Four little Soldier Boys going out to sea; A red herring swallowed one and then there were three. Three little Soldier Boys walking in the zoo; A big bear hugged one and then there were two. Two little Soldier Boys sitting in the sun; One got frizzled up and then there was one. One little Soldier Boy left all alone; He went out and hanged himself and then there were none. note* The poem used to include the reference to Indian Boys,opposed to Soldier Boys, along with the change from Indian Island to Soldier Island due to supposed racism issues.
Postscript by the killer
In a postscript, a fishing ship picks up a bottle (containing a written confession) inside its trawling nets, which is sent to Scotland Yard and explains the events, but has been left to chance whether it will be discovered.