South opened One Heart, West overcalled with Two Diamonds, and North bid Three Diamonds. The obvious raise to Three Hearts would have been purely pre-emptive - the cue-bid showed a genuine raise to at least Three Hearts. Although South held the least attractive 15-count, he jumped to Four Hearts.
Against the heart game, West led the ace and another club. South won and started on trumps, but the worst happened when East won and led another club for West to ruff with his 10 in front of dummy. Now, what should declarer discard? A useless spade or a useless diamond? Declarer chose a diamond.
West solved this problem. Judging that a spade lead would now be fatal, he tried a diamond. This gave away a trick, but the defenders still had to come to a spade at the end and the contract failed. Any better for declarer to part with one of dummy's spades? No, for then West, although end-played for a trick, can exit with a spade, coming to a diamond at the end. I expect you've got there: discard a low trump under West's 10! West, say, exits with a diamond but now declarer takes his two diamond tricks and plays the rest of his trumps, squeezing West in spades and diamonds, for dummy's six of diamonds is still there as a menace and West has to part with a spade to give South three tricks in the suit.