N/—		♠	10 8 7 3
		♥	A K 7
		♦	Q 10 8 5 4
		♣	J
♠	K Q J 4
♥	10 5
♦	J 3
♣	Q 10 8 6 4

¹ 19-21
² Puppet Stayman: enquires after South's holding in the major suits
³ Neither a four-card nor a five-card major suit
⁴ Quantitative raise (invitational to 6NT), therefore not forcing
⁵ Maximum

Optimistic bidding by North! Even if South has the maximum 21 points, the sum in NS still only adds up to 31. On the other hand: North's five-card suit is often valuable but 6♦ might be better...

Of course West leads the ♠K, which wins.
It is time for West to show what stuff he is made of. Which card does he play at trick two?

Solution

West tries to picture South's hand. Since South has shown a maximum, he must have the remainder of the points. So the layout may be something like:

N/—		♠	10 8 7 3
		♥	A K 7
		♦	Q 10 8 5 4
		♣	J
♠	K Q J 4			♠	6 2
♥	10 5			♥	9 8 6 4 3
♦	J 3			♦	7 6 2
♣	Q 10 8 6 4			♣	7 6 3
		♠	A 9 5
		♥	Q J 2
		♦	A K 9
		♣	A K 9 5

This is only an example, South can have many more different distributions. What matters is, that he has at most three hearts and three spades (East can have the ♥J but that is irrelevant since South has denied a four card heart suit; therefore declarer makes exactly three heart tricks, no less no more).
The danger is South holding the ♣9 (or five clubs).

After all, which tricks will declarer take? A spade, three hearts, five diamonds and two clubs. That adds up to eleven. But observe what will happen if West continues with the 'obvious' ♠Q: declarer wins, cashes the ♥AKQ and then the diamonds. With the last diamond to go, the situation is:

N/—		♠	10 8
		♥	—
		♦	8
		♣	B
♠	J			♠	—
♥	—			♥	9
♦	—			♦	—
♣	Q 10 8			♣	7 6 3
		♠	9
		♥	—
		♦	—
		♣	A K 9

♦8 is played from dummy, South discarding the ♠9. And West? If he throws the ♠J, dummy's ♠10 becomes a master. If he throws the ♣8, South makes ♣AK9.
Can West prevent this? Yes, at trick two he must play a club. This way declarer lacks communication for this squeeze, for that technique requires an entry card in clubs in the South hand at the crucial moment. Of course West does not play a small club (dummy's ♣J would become declarer's twelfth trick) but the ♣Q.

South now does not stand a chance, provided West and East (!) keep on defending well. After all, declarer will do his utmost by taking West's ♣Q with the ♣A and cashing eight red tricks. After that, there are still three cards to play. South will have left:
- Either ♠A ♣K9: West then must have kept ♠Q ♣108
- Or ♠Ax ♣K: West then must have kept ♠QJ ♣10.
How is West to know what South has got left (don't forget, South can have many different distributions, the diagram above is only an example)?
This is where East comes in. By signalling his distribution in the black suits (in the diagram above: spades 'even', clubs 'odd'), East informs his partner about the layout. West should of course pay attention to South's discards on North's red tricks as well!