The idea, of course, is to make this contract if both diamond honors are with East without jeopardizing the contract if they aren’t. Start by cashing the ♥A Q, cross to the ♠10, ruff a heart and draw West’s last two trumps, overtaking the ♠Q if necessary. The table is set. Now lead a diamond to the 10 assuming West plays low. After East wins the trick, East is in trouble. Unless East started with four hearts (!) and exits a heart, forcing you to take a second diamond finesse, East is in serious trouble.
A diamond goes straight into “Jaws” (dummy’s ace–jack), and a club is no better. A high club is ruffed and the ♣Q provides a resting place for your third diamond, while a low club will be ducked to the queen as you shed your losing diamond.
And no, a diamond lead doesn’t beat it either: Finesse the ♦10, win the heart return, play the ♠A, cash a second heart, return to your hand with a trump, ruff a heart high, cash the ♦A (important) and then play all of your trumps and the ♥K, reducing to the ♦9 and a club. Dummy has the ♣A Q and East has been squeezed on the last major-suit winner. If he holds on to a diamond honor, the ♣K will drop. If he discards a diamond honor, your ♦9 is high. That ♦9 turns out to be a big, big card.
Thanks to Tim Bourke, Australia, for this one.