Bridge by Frank Stewart
"If West had overcalled one spade, I could accept a raise to two hearts. But over two spades, my partner didn't have enough to bid three. Moreover, his trump support was poor, and West's preempt made bad breaks likely."
Against four hearts, West had led the ten of clubs. South won and took dummy's top spades to discard his last club. He next led the ace and a low diamond, and West won with the ten and led another spade. East threw his last diamond.
South ruffed and knew if he ruffed a diamond in dummy, East could overruff. So South took the A-K of trumps.
An opposing preempt can force you to stretch your values to avoid being shut out. North's bid was aggressive but reasonable. If he had held A K 7 6, 10 5 4, 8 2, A 5 4 3, he would have bid four hearts.
South was to blame for the result, since his game was cold. After he ruffs West's spade lead at the sixth trick, South must cash only the ace of trumps, then ruff a diamond in dummy.
East can't prevail by overruffing. If he discards, South returns dummy's last trump to his king and leads good diamonds. He maintains control and loses two trumps and a diamond.