Opening lead: jack of diamonds
West's two-no-trump bid was unusual—and unwarranted. North's jump to four spades was preemptive. East's four-no-trump bid was also unusual, announcing support for both minors. South decided to let the opponents do their guessing at the seven level.
They elected to defend, and declarer won the first trick with the ace of diamonds and drew three rounds of trumps, ending in dummy. With no adverse bidding, declarer would have led a low heart to the queen, playing for a favorable location of the ace and a split of the suit, or the fall of the jack. But since West had trotted out the unusual no trump on two weak suits, the fact that he had followed to three rounds of spades almost guaranteed his void in hearts. So declarer's first lead from dummy was the 10 of hearts. East ducked; South did, too. It didn't matter what East played; his jack and 9 were trapped. With declarer able to get back to dummy twice via diamond ruffs, East could win only one heart trick.