If you have ever watched a bridge expert in action you may have marveled at the way he seemed to know just where all the high cards were. It wasn't extrasensory perception, nor were the cards marked. With a sharp ear and a little thought, anyone can learn to locate the high cards. Let me show you.
South's four-spade bid was much too ambitious. But you are in four spades with South's hand and it's up to you to do your best.
On West's opening lead of the diamond king, East signals with the 9. West continues with the ace and queen, and East follows with the 2 and 8. You ruff the third diamond. Now, knowing that West does not open four-card majors, how much do you know about East's hand?
Well, you know he has exactly one heart, because if he were void he would want to ruff a heart and so would not have signaled for West to continue diamonds. He probably does not have five spades or he might have mustered up a one-spade bid. But the odds are against an even division of the spades, and if East has four he is a 2-to-1 favorite to hold the jack.
So you decide to take a spade finesse and you lead a club to dummy's king, with West alertly playing the jack and East playing the 10. West might have started with queen-jack alone in clubs, but you are inclined to think that he is merely unblocking to avoid a possible end play and East is signaling that it is safe for West to continue to do so. You win dummy's king of clubs, finesse the spade 10, and when it wins you continue trumps, West showing out on the third round. On your fourth trump lead, which draws East's jack, West completes echo discards of the 6 and 4 of hearts.
So far, so good. You have proved that East began with a 4-1-4-4 distribution and your only difficult decision was whether to play East for the jack of spades. But your contract is not yet home, because you still have a club loser and a heart loser. However, you now have a blueprint of the way the cards must be if you are to make the hand.
If you could make West win the third round of clubs, he would have to lead a heart and you could avoid a heart loser. But West has been told it is safe to unblock by dropping his queen if you cash your ace of clubs, so that play can't work. What else?
If East began with a singleton king of hearts, you needn't lose a heart trick. But that wouldn't leave West much of a bid, and surely he would not be so anxious to evade an end play if he did not have the heart king. You are down to just one other hope: East's singleton has to be the jack or the 10.
Now you're ready to make that extrasensory-perception play. You lead the queen of hearts and when West covers with the king you duck the trick. You hold your breath for a moment until East produces his card. It's the 10 of hearts, just as you had hoped.
Now it doesn't matter what West returns. Presumably he'll lead the queen of clubs. You win it with the ace, and perhaps you cash your last trump. West's discard of the 2 of clubs confirms your diagnosis. You lead your 5 of hearts and finesse the 9 when West plays low. The ace of hearts wins the last trick, taking care of your losing club and letting you make your contract.