Before the beginning of a session, duplicate bridge players are required to fill out a card listing their conventions. The fact that some players use so many as to overload their convention cards gave rise to the rule that when someone makes an unusual bid his partner is required to tap the table and call "Alert!" The next player, thus warned that the bid he has just heard does not mean what it sounds like, then has the right to ask for an explanation before taking any action.
I am going to alert you to the meanings of the conventions used in this deal, which helped decide the 1974 Men's Pair Championship. Then it will be your problem to select an opening lead from the West hand, so I suggest you cover the other cards until you have learned about the "comic no trump" and "western cue bid" used in the auction.
Each of the bids marked with an exclamation point was accompanied by a table rap and a call of "Alert!" East's initial bid was the comic no trump, indicating either a genuine no-trump overcall or a hand on which one would ordinarily make a weak jump overcall in an as yet unspecified suit. South's double told North that East had the second type of hand, and East's retreat to two spades confirmed the picture. South's bid of three clubs was highly encouraging; he had already shown some values by his double, and with only a fair hand he could have passed, leaving further action up to North.
The next table rap came when North bid three spades—a western cue bid announcing a partial stopper in spades and suggesting that South bid no trump if he could bolster the suit with a partial stopper of his own.
East's double of three spades wasn't just a nuisance action. It, too, required an alert because it was being used as a convention to guarantee either the ace or the king of the suit. South's three-no-trump bid, answering North's inquiry, then ended the auction.
As West, you now know a great deal about the hand. North's western cue bid of three spades and South's no-trump response have told you that one opponent has queen-small of spades as his partial stopper and that the other holds three spades to the jack. You can be sure of this because your partner's bidding has shown a six-card suit including the ace. You also know that East is likely to be devoid of high cards outside of the spade suit, but you have a sure reentry for your side in the ace of clubs.
Did you figure out, as West did, that in this special situation your lead should be the 5 of spades rather than the customary king? Look at the full deal. When declarer played a low spade from dummy, East inserted the 9 and South took the jack. He next ran off four tricks in hearts, using a diamond to get to dummy. Then, rather than give up, he led a club hoping to establish a ninth trick. But West won with the ace and returned the king of spades, engulfing dummy's queen, whereupon East overtook with the ace and cashed four more spade tricks for a two-trick set.
South didn't see it right away, but he could—and should—have foiled West's brilliant lead by playing dummy's queen of spades to the first trick or, as the cards lie, by refusing to win the first trick. (If East had held six to the ace-king and ducked, there would be nothing declarer could do about it.) But with this layout it wouldn't have helped East to duck and the contract could not have been defeated. In fact, declarer would have made four no trump instead of being set at three.