West   North   East   South
                                 1♠
pass     3♠       pass    4♠
all pass

You receive the ♥K lead against 4♠. Plan the play (trumps are 2-2).

Solution:
A reasonable start would be to win the opening lead with the ace, play a spade to the queen and a spade to the ace, discovering that trumps are 2-2. A heart should be ruffed in dummy. Now, the contract can be guaranteed by playing a diamond to the ace, and playing a diamond back towards the jack. Here are the two possibilities:

West wins the trick with the ♦Q (or ♦K): If West cashes the ♦K, then dummy's jack will take care of a losing club. If West plays a small diamond, you will stick in the jack from dummy, which is likely to be won by East's king. This will mean that diamonds are 3-3, and you can discard one of your clubs on dummy's thirteenth diamond.

If West instead switches to a club, you should cover cheaply in dummy (i.e. if West plays a low club, you should play the eight, if West plays the jack or ten, you should cover with the queen). When East wins the trick, he will be endplayed. A club return will give up an immediate trick. If he cashes the ♦K, or plays a diamond to West's king, he will establish dummy's jack for a club discard.

East Wins the diamond: In this case, East can once again be endplayed. A club return is once again fatal. If East has four diamonds, and cashes top diamonds and tries to cash a fourth high diamond, you will discard a losing club from hand as dummy follows with a diamond, forcing East to play a club or concede a ruff and discard. Which brings us to another point - when you play the ♦A and a diamond, if West follows with the ten, you should cover with dummy's jack. It would be fatal to duck in dummy as West would then switch to a club.

Analysis:
Bridge Baron's double dummy solver confirms that the contract cannot be defeated on any lie of cards if the recommended line of play is adopted.

Bridge Baron's Line of Play
Bridge Baron finds the winning line of play this week as well. Bridge Baron won the heart lead in hand, ruffed a heart in dummy, drew two rounds of trumps, and played the ♦A and a diamond, covering West's ten with the Jack. When East won the queen and played the ♦8, Bridge Baron introduced a variation. Bridge Baron ruffed this trick and played a club to the eight, endplaying East.
Par Contract Analysis:
On the actual lie of cards, the par contract is 5♠ by North-South. It should be noted that 11 tricks are possible only by double dummy lines.

Bridge Baron deal No : N0916-41972-04673-86552-27119-48481