Two defenses, but neither works
Ambrose Bierce, author of “The Devil’s Dictionary,” claimed: “Calamities are of two kinds: misfortunes to ourselves, and good fortune to others.”
In this deal, there are two possible defenses against four spades, but neither will work if declarer plays correctly. What are those defenses, and how can South survive?
East might have opened one no-trump, adding a point for his good five-card suit. (The Kaplan-Rubens method evaluates the hand at 16.2 points because it likes strong fivecard suits, aces and kings.) Then, maybe South would have overcalled three spades, but the lack of a singleton would have been a tad worrying. If South had passed, North would presumably have doubled in the fourth position, and South would have bid two or three (or four!) spades.
After East preferred to open one heart, South overcalled three spades to show a good seven-card suit and some 5-9 high-card points. North bid game, hoping for the best.
West leads the heart queen. East might overtake this, cash the heart ace and continue with the heart 10, hoping West can gain a trump promotion. But South ruffs high and plays a spade to the jack. Declarer ruffs the next heart high, draws trumps and claims, discarding his diamond loser on dummy’s third club.
Alternatively, East lets his partner take the first two tricks, then West shifts to the diamond jack. South, realizing that the finesse is doomed, wins with dummy’s ace and immediately takes the club winners to sluff his second diamond. Then he concedes one trump trick.