Climax:
All ten people have been killed, and as per the nursery rhyme, their bodies have been arranged, one by one, in a symbolic ritual surrounding the centerpiece dining table to complete the fatal game. The only evidence left is a tape recording of the mysterious U.N. Owen revealing that each had guilt associated with their past that required retribution; the recording implicates Justice Wargrave as the mastermind behind their deaths.
Wargrave, who is now the sole survivor of the group, confesses that he planned the murders as an act of justice to punish the ten individuals for their heinous crimes that went unpunished by the law. He explains how he carefully constructed the elaborate setup to ensure their fates while manipulating them to turn on each other, culminating in their collective demise.
Falling Action:
Inspector Maigret arrives on the island to investigate the massacre. He finds the bodies and the tape recording, leading him to discover Wargrave's confession and the truth about the murders. In a dramatic twist, Maigret discovers that Wargrave has taken his own life, using a gun hidden within his secret room.
As Maigret concludes his investigation, the true nature of the victims' crimes and their individual guilts are revealed through flashbacks. The novel ends with Maigret and the local inspector, Detective Superintendent William Blore, pondering the philosophical implications of the events, discussing whether justice can truly be served outside the bounds of the law, leaving readers with a haunting sense of moral complexity and the far-reaching consequences of past misdeeds.