Four volunteers from the audience are asked to help. They are handed all five keys to play with.... I mean, try in the lock. while all of the keys appear alike, four of them are cut slightly off so they can not open the lock. One key works perfectly. "The other reason these keys are so large is that it make it impossible to do any sleight of hand with them" Says the magician. One of the volunteers is asked to secretly mix five envolopes. One is asked to secretly mix all five keys in a paper bag. One is asked to stand and hold the lock so the audience can see it. The last is asked to donate a hundred dollars. Failing to do so, they are requested to secretly take the keys, one at a time, from the bag and drop them in the envolopes.

The magician recaps "Only one key works. They were mixed by one volunteer and placed in envolopes mixed by another volunteer. There is no way anyone here including myself can tell you where the correct key is". The envolpes are then placed, one at a time, against a numbered board sitting on a thin tray. The volunteers are asked to join the magician on the stage for some fun.

Each of the four spectators is asked to name a number from one to five. The key at that number will be the key they select. Each volunteer then tries their key in the big lock to see if it works. The magicain who is left with the fifth key always opens the lock. If a few hundred dollars is put up as a reward for getting the correct key the magician will always keep his full fee for doing the show since he always opens the lock.