Disappearance of Dr. Armstrong

The disappearance of Dr. Edward George Armstrong is the crucial turning point in the final phase of the Indian Island murders, an event that simultaneously reduces the living suspects to three and reveals the killer's method of manipulating trust to achieve the impossible. It is the moment when the carefully constructed illusion of a hidden madman collapses, replaced by the terrifying realization that the murderer must be one of the last survivors—and that one of them has just been eliminated without a trace.

The Setup and the Rendezvous

After the staged death of Lawrence John Wargrave, which the judge himself engineered using a red curtain, grey knitting wool, and a fake wound, the remaining four people—Vera Claythorne, Philip Lombard, William Henry Blore, and Dr. Armstrong—were trapped in a state of heightened suspicion. Wargrave, now believed dead, had secretly recruited Armstrong as an ally. He had hinted to the doctor that he had a scheme to trap the murderer, and Armstrong, who knew Wargrave by reputation as a respected judge, found it inconceivable that a man of his standing could be the killer. Wargrave's plan was simple: he would pretend to be the next victim, allowing him to move about the house and spy on the others. Armstrong, convinced of Lombard's guilt, agreed to the ruse. The fake death scene was set that evening, and it worked perfectly, with Vera Claythorne's scream over the seaweed in her room drawing everyone upstairs while Wargrave took his pose. After being carried to his bed, Wargrave arranged a rendezvous with Armstrong outside the house at a quarter to two in the morning.

The Murder on the Cliff

Wargrave met Armstrong on the edge of the cliff behind the house, a spot chosen for its privacy and the fact that the bedrooms faced the other way. Armstrong remained completely unsuspicious, still believing he was part of a plan to catch the real murderer. Wargrave, feigning discovery, uttered an exclamation and leaned over the cliff, telling Armstrong to look at what appeared to be the mouth of a cave below. When the doctor leaned over to look, Wargrave gave him a quick, vigorous push, sending him off balance and into the heaving sea below. Armstrong drowned, his body later washing up wedged between two rocks. The method of his death was a direct fulfillment of the nursery rhyme's seventh verse: "Four little Indian boys going out to sea; A red herring swallowed one and then there were three." Wargrave himself noted in his confession that Armstrong had "taken the red herring all right," meaning the doctor had been deceived by the false promise of a hidden cave and had swallowed the bait of Wargrave's trust.

The Illusion of Disappearance

After killing Armstrong, Wargrave returned to the house. His footfall was heard by Blore, who was awake and listening. Blore saw a figure pass through the front door and, suspecting a trap, did not immediately pursue. Instead, he checked the other rooms and found Armstrong's door locked from the outside, confirming the doctor was not in his bed. Blore then woke Lombard, and the two men went in pursuit of the figure they believed to be Armstrong. They searched the island thoroughly in the moonlight but found no trace of the doctor. When they returned to the house, they discovered that a pane in the dining-room window had been smashed and that only three little china Indian figures remained on the table, suggesting Armstrong had met his fate. The illusion was complete: Armstrong had vanished, leaving the three survivors—Vera, Lombard, and Blore—to suspect each other. Wargrave, meanwhile, had returned to his room and laid himself out again on his bed, once more playing the part of a corpse.

Consequences and Revelation

The disappearance of Armstrong had a profound psychological effect on the remaining three. It shattered any remaining hope of a rational explanation and intensified the paranoia that would lead to their own deaths. Blore and Lombard, now openly distrustful of each other, began to argue over the missing revolver, which Wargrave had secretly returned to Lombard's drawer. Vera, who had suspected Armstrong all along, felt vindicated but also more terrified. The event set the stage for the final, desperate acts: Blore's return to the house alone, where he was killed by the falling marble bear clock; Vera's shooting of Lombard on the beach; and her subsequent hanging in her bedroom, a scene Wargrave watched from the shadows of her wardrobe. Armstrong's body was later found by Vera and Lombard, washed ashore and wedged between rocks, confirming that he had been dead all along and that the murderer was still among them. The discovery of the body, and the realization that only two of them remained, directly precipitated the final confrontation between Vera and Lombard.