The magician borrows a coin from a volunteer in the audience. The volunteer marks the coin and the magician makes the coin vanish. So far nothing unexpected.
Now the magician takes a match box secured with rubber bands out of his pocket and opens it. Inside is another match box. The second match box is opened to reveal a small cloth bag inside. When the bag is opened the signed coin is unexplainably inside!
The instructions for this amazing revelation are easy to read
The trick itself is also easy to perform once you know how.