Take a close look at the magical black box. There is a small magnet supplied that when stuck to the inside of the box will reveal a magnetic flap. This flap will make a playing card vanish.
Begin by placing the card in the magic box and making sure prior to doing so that the flap is removed and ready to be shut against the playing card. The magic then happens and you shut the box. When opening it again the playing card is now underneath the secret magnetic flap that only you can get out with the secret magnet supplied.