East opened Three Hearts, South overcalled with Three Spades, and North (who though he had a little in hand was aware that his partner might have been stretching a little) contented himself with a raise to game.
West led the jack of hearts against Four Spades and East, after cashing his king and ace, led a third heart. He chose the two, not so much to suggest something in clubs, rather more to dissuade his partner from opening up the diamond suit.
West now spent some while looking at declarer's 10 of hearts. With the fixed idea that his partner held the king of clubs, either discarding or ruffing with the king would allow dummy's presumably losing club to go away. He finally chose the third (and disastrous!) option when he ruffed low. Dummy over-ruffed, a spade lead exposed the position and, after winning with his ace and cashing his two club tricks, South exited with a trump to West's now lone king. It was all over - West now had the choice of conceding a ruff and discard or leading a diamond away from his king.
Now West, really! Was it conceivable that your partner has, non-vulnerable, opened Three Hearts with a seven-card suit headed by the ace and king, and with an outside king in reserve?