Playing a variable no-trump, East opened One Heart. South bid One Spade, West passed and North bid Two Hearts (an unassuming cue-bid, suggesting a raise to at least Two Spades based on high cards rather than distribution). With a six card suit and a little to spare, South stretched to Three Spades and North went on to Four.
West led the four of hearts. East took his two heart tricks and continued with the ten. Declarer ruffed successfully with the nine and followed with a trump to the king to expose the position in the suit. After picking up East's queen, South played three rounds of diamonds, ruffing the third on the table while East followed with the ten, jack and queen.
Dummy's last heart was ruffed in hand but, when the ten of clubs was led, West played low. Should declarer finesse, or try dummy's king?
The point is that by now East has shown up with 12 points. He may hold both the ace and queen of clubs, in which case there is no hope but, if he holds 2Q x x or 2A x x, it must be the latter, for with 4Q 10 6 !A K 10 9 &Q J 10 2Q x x, he would surely have opened One No-trump. All the clues suggest the winning play of letting the king of clubs run.