Magician displays four large Aces (the Ace of Diamonds, Clubs, Hearts and Spades) in a fan.
He squares the fan, and places the four cards in an empty plastic cover.
 
He now takes out three cards from the cover, one by one, and shows them front and back. The three cards are the Ace of Diamonds, Clubs and Hearts.
 
The magician asks the spectators which Ace is left behind in the cover. The spectators obviously call out the "Ace of Spades".
 
The magician disagrees with them saying "No, that is wrong". After some argument he removes the last card from inside the cover and shows it to the spectators. Surprise! It is a card with the word WRONG printed in large letters!
 
The clever spectators ask the magician to show them the back of the card, or turn it over. After some by-play, and apparent misunderstanding, the card is turned over.
 
It reads "WRONG AGAIN". The cover is shown empty and may be tossed out for examination.
 
Magician states that the Ace of Spades has in fact travelled invisibly from the cover into his pocket! He dramatically removes the vanished Ace from his pocket!