South led the club jack from dummy and threw a diamond.

South threw dummy's heart king, and East smoothly gave up the club seven.

After a heart lead, South would have thrown a club from the dummy.

But what if South throws a heart in the diagramed position?

South threw the diamond queen and thought he was safe.

East did not cover with the queen, and South threw a club.

West captured the king with the ace and played a second club, on which South threw a heart.

South threw a club, allowing East to win with the nine.

It is interesting to consider what would happen with the actual distribution if South throws a heart on the first club lead.

The heart nine was led, and South threw a diamond, allowing the ace to win.