The Morton’s Fork Coup is a well-known maneuver that permits declarer – in the right circumstances – to get rid of a loser in a trump contract by offering a no-win choice to a defender. Here’s the general situation – observe the layout of this suit:
Declarer, South, leads a low spade (which is not the trump suit) toward the dummy. If West rises with the ace, declarer will have no more losers in the suit. If West ducks, however, declarer will win the queen and may be able to later discard dummy’s remaining diamond on a winner in a different suit. Whether West rises or ducks, he can only score one trick. Damned if he does and damned if he doesn’t, West is impaled on the twin tines of Morton’s Fork.
On the following deal, Norwegian master Geir Helgemo shows the fork in action.
Helgemo, South, was declarer in 4♠. West led the ♥10 to declarer’s ace, and the ♠K was captured by East, who then played the ♣J. Helgemo ducked. The club continuation was won by South, who next drew the remaining trumps with the ♠J and ♠Q. A low diamond was then called from dummy.
East was fixed. If he rose with the ace, declarer would make his contract by losing only one diamond and two clubs. So East ducked, but Helgemo had an answer to that as well. Winning the ♦K, he cashed dummy’s high hearts, pitching a diamond from the closed hand, to create this ending:
When the ♦Q was played from dummy East won the trick, but then had to concede a ruff and discard, allowing Helgemo to shed the club loser in dummy.