Assume you’re East and partner leads a heart against three notrump. You take the ace and realize that a heart return would be pointless, since it is impossible for partner to have a holding where a heart return would be beneficial. Your best chance, therefore, is to shift to your own suit, spades.

But it is also clear that in returning a spade you should not make the normal lead of your fourth-best card. There is too good a chance that declarer has three to the king, in which case he would play low from his hand and acquire an extra spade trick.

The best way to try to beat the contract is to lead the queen of spades at trick two. You hope South has K-x-x or K-x of spades and partner has an entry card, in which case he can eventually return a spade through dummy’s J-9 after South has taken the queen with the king.

In the actual case, this approach would succeed if declarer went along with your scheme by playing his king at trick two. He could cash eight tricks in a row but would then run out of steam and finish down one.

But South can defuse your scheme by ducking the queen of spades when you lead it. He might see what you are trying to do and apply the suitable countermeasure by allowing your queen to win the trick.

Once declarer does this, he will inevitably prevail, but you should nevertheless feel satisfied that you gave your all to stop the contract and unfortunately met a foreman worthy of your steel.

Tomorrow: The science of card-reading.