Three-card Monte is a confidence game in which the victim, or mark, is tricked into betting a sum of money, on the assumption that they can find the money card among three face-down playing cards.
In its full form, Three-card Monte is an example of a classic short con in which a shill pretends to conspire with the mark to cheat the dealer, while in fact conspiring with the dealer to cheat the mark.
This confidence trick was already in use by the turn of the 15th century, having a great deal in common with the shell game; they are the same except that cards are used instead of "shells".
The trick to Three Card Monte is that the Queen is never really on the table.
(This is not correct - the Queen is on the table, but the mark is not allowed to win by betting on the correct card.
If the shill bets on the correct card, one of the shills will "bet" a larger bet. The dealer will accept the larger bet and "pay" the shill who "won".)
There are many other ruses that are used to scam people.
This game can be deceptively played by sleight of hand alone,
but on the streets it is much closer to a mugging than a game of skill and chance.
In the "The Three-Card Monte Job", the scam is one of Jimmy Ford's favorites. So much so he uses the same scam on a grander scale. Making the "mark" believe he is robbing not only a bank, but three banks. This distracts the police, while he pulls his real con on his real target, the Boston Police Department Ninth District.