Fancy dress

Fancy dress (or Fancy dress party) involves people dressing up in costume to resemble someone or something else. As a plot device it can be used to hide the identity of the culprit, or make it appear that someone else is the culprit. An elaborate costume can also be used to either hide a weapon, or give someone a reason to carry a weapon.

Fancy dress in the works by Agatha Christie

 * During the Victory Ball, a group of friends dress up as characters from the Commedia dell'arte. At one point two of them were dressed as Harlequin. (The Affair at the Victory Ball)
 * Sir Richard Haydon is stabbed to death during a fancy dress party at his home near Dartmoor. (The Idol House of Astarte)
 * Tommy and Tuppence Beresford attend a fancy dress party at the Ace of Spades nightclub after reading an advert in the Daily Leader. (Finessing the King/The Gentleman Dressed in Newspaper)
 * During a fancy dress ball at Charnley, Lord Charnley took his own life. Fourteen years later the mystery was solved. (The Dead Harlequin)