What is the skeleton in closet The Novel And Then There Were None?

The skeleton in the closet in the mystery novel And Then There Were None by Agatha Christie is the metaphorical representation of the dark secrets that each character in the book is hiding. These skeletons are the hidden sins and lies that eventually come to light as the characters are killed off one by one. The titular line, "And then there were none," echoes the notion that their hidden pasts ultimately catch up with them, leaving no one left alive on the island.