The magician cuts the deck in half, and gives you half and keeps the other for him self. You are then asked to follow every move. Both put the deck behind your backs. Both select any card from your decks and swap them with the other with out looking at them, you then both place the swapped cards face up any where in your decks. You then repeat this selecting, swapping and placing routine one more time. The two halves are brought back together and spread across the table to reveal that all four aces have been selected and can be seen face up in the deck.
Aces on top of your deck before the start
The final layout
The secret is before you start the trick have all four aces in your back pocket and put them on top of the deck you keep. When the volunteer gives you their card give them an ace, and put theirs on the bottom and take another ace and place it in your deck face up. Just repeat this again for the second time.