West   North   East   South
                                 1NT
pass     2♣      pass    2♥
pass    3NT     pass    4♠
pass     6♠      all pass

North's bidding was ambitious, to say the least! The final contract fortunately is a reasonable one. West leads the ♦5 (fourth best leads), East wins the ace and returns the ♦3, West following with the four. You play a spade towards dummy, and West plays the queen, you win the ace. How do you plan to take care of the two club losers in hand?
Solution:
Now that your problem in the spade suit got resolved, all you need to do is find a way to take care of your two club losers in hand. The ♦Q will take care of one of them. If the diamond jack falls under the queen, you can discard dummy's fourth diamond on the other club. However, West's diamond play suggests that diamonds are 5-2 either way (West either led from a doubleton, or made a fourth best lead and followed with his lowest card the next round), and this plan is liable to fail. Another other option is to rely on the club finesse, a 50% shot.

There is a third option, which is by far the best. If East has four or more hearts, then you can discard all of dummy's clubs on the top hearts, and crossruff the rest of the hand. After winning the ♠A, you should unblock the ♥J. Say you try the ♦Q now, East ruffs in as predicted, you overruff. You then play off the ace-king-queen of hearts discarding three clubs, both opponents following. You then crossruff the hand.

Did you notice that East could foil the above plan? When you play the ♦Q from dummy, East can discard one of his hearts, thereby thwarting your line of play. Therefore, testing the diamond position by playing the ♦Q is not optimal in theory. If you believe that West led from a five-card suit rather than a doubleton, you can play on hearts without testing the diamond position. Even if you do test the diamonds by playing the queen, a vast majority of players sitting East would not consider discarding a heart.

You might have observed that this is another position where West might falsecard the ♠Q from Q10 doubleton. You can't cater to the situation where West falsecards the queen from Q10 doubleton as well as take the recommended line of play; if it turns out that West did falsecard, all you can do is congratulate him on his fine play.

Analysis:
Bridge Baron's double dummy solver confirms that the only successful line on the lie of cards is to play four rounds of hearts discarding clubs, and then cross-ruffing the rest. The double dummy analysis also affirms that declarer cannot afford to test the diamond position by playing the ♦Q, as a heart discard by East does indeed scuttle the contract.
Par Contract Analysis:
The par contract is 6♠ by North-South.

Bridge Baron deal No : N4702-58596-18766-31770-09346-84767