It would be a (common) mistake for South to open the bidding with 4. That is a preemptive opening and South’s hand is much too strong. A 4 opening should look more like KQJxxxxx of hearts and nothing on the side. With 17 HCP, South shouldn’t preempt. At the other end of the spectrum, a strong 2 opening is possible. I’d prefer to have more HCP, so recommend starting with 1.
West can use a popular convention: The Unusual 2NT. This bid is used only after the opponents open on the 1-level. A jump overcall (it must be a jump) to 2NT (not to 3NT) shows a 2-suited hand. The suits should be at least 5 cards in length. Which 2 suits does it show? The 2 lowest-ranking unbid suits. So if the opponent’s opening bid is 1 or 1, a jump overcall of 2NT shows both minors. The bid is intended as weak/preemptive. West’s hand qualifies. Note that all of West’s HCP are in his long suits—this makes the preemptive 2NT more attractive than if West’s hand were: K KQ xxxxx xxxxx.
What should North do after 2NT? A double would be penalty-oriented, and that is one possibility. In the diagram, North is shown as passing. He can’t bid diamonds naturally, since that is the suit his opponent has shown.
East should choose a minor, and has an easy choice. Even with only three clubs, East would take out West’s 2NT to clubs. On a really bad day, East might have only two clubs and one diamond—in which case he has to grit his teeth and take out 2NT to 3 (he can’t let his partner play in 2NT)!
South has a very strong hand and a great suit. He has enough to bid again on his own. He could bid a conservative 3 (he has 9 tricks in his own hand), or maybe even jump to 4. After bidding only 3 (as shown), he gets raised to 4. North has not one, but two aces—much more than he could be expected to hold. He should believe his partner’s free 3 bid (which shows a strong hand) and raise him to game. South showed a long/strong suit with his three-level rebid, so North’s singleton heart shouldn’t be a worry.
West has lots of attractive lead choices. He could lead his singleton spade (when on lead against a trump contract, I am usually okay with a side-suit singleton). A three-card sequence (such as KQJ or QJ10) would also be desirable. Two honors in a row is a decent lead, but not always safe. West could lead the K from KQ or the Q from QJ. Since his partner chose clubs, let’s say he starts with the Q.
Declarer doesn’t have much to think about. He will lose the club trick and barring a 5-0 trump split, his only other possible loser is in diamonds. If the defense continues clubs, declarer will have an easy time. He will ruff the second club and draw trump. Then, he can unblock his KQJ. He can cross to dummy in diamonds and discard his other diamond on the A—12 tricks.
Can the defense prevent the two overtricks? Yes, but it isn’t easy. The defenders need to knock out dummy’s A (the entry to the A) before declarer gets to unblock his KQJ. If East lets his partner hold the first trick, probably West should find the K play at trick two (it can’t really hurt). Alternatively, East can overtake the Q and shift to his singleton diamond at trick two. If the defense doesn’t find that trick-two diamond play, they are resigned to -480. There are lots of tempting plays (singletons and sequences) that could easily dissuade the defenders from finding that killing diamond switch.
1) Opening 4 of a major is weak/preemptive. Don’t do so with 17 HCP.
2) A jump overcall of 2NT shows 5-5 in the two lowest unbid suits.
3) After partner shows a two-suiter, you should bid your longer of his two suits.
4) If opener rebids freely on the 3-level, he shows a strong hand with extra values.
5) Leading a side-suit singleton against a trump contract is usually wise (though it wouldn’t work well on this real deal).