Opening lead: king of hearts
East violated a principle that the dealer at the other table had observed: he opened with a preemptive bid in spite of holding a two-suited hand. But thanks to considerable cooperation from North, it worked out to a big profit. South's four-no-trump bid was a powerful demand. West's double was a questionable tactic; he might better have bid five spades. But this, too, worked well when North did not bid five diamonds.
South's pass of six spades was forcing. North now had a chance to bid seven diamonds or seven hearts. Instead, he doubled. The six-spade contract was beatable if South had found the club opening. When he opened a heart, however, East ruffed, drew trumps and made all 13 tricks. The team total yielded 24 IMPs, the maximum for any hand. At $3 an IMP, this cost each loser $72.
When you have bid strongly, a pass of a very high bid by the opponents is a forcing pass, but if partner's next bid would put you in a grand slam, you must have first-round control of the opponents' suit.