Another Basic Slam
A 10 4 3 2
K J 8 3
J 2
9 7
K 9 7
10 5 2
9 6 5 3
Q 4 3
J 6 5
Q 9 4
10 7 4
10 8 6 5
Q 8
A 7 6
A K Q 8
A K J 2
A
6 ♥ contract fails because North/South must lose a heart to the defense, and
can't time that loss so that the defense must break the spade suit.
6 NT fails because there are nine top tricks and the situation in
the spade suit means that suit cannot be set up for extra tricks
without losing two spades, while there is only one extra trick
in each of hearts and clubs.
Indeed, the only slam to make on this deal is
6 ♦.
Say the defense leads a diamond. Declarer wins the
♦ J and plays the
♣ A-K and ruffs a club, crosses to the
♥ A, draws trumps, and ducks a heart. Declarer gets three hearts, a spade, four diamonds, three clubs, and a club ruff.
My original line was more complex - thanks to Richard Pavlicek
for pointing out this far simpler line.