Opening lead: 10
Bidding commentary: As North, you have the strength for a positive response in hearts, but the ugliness of your suit should deter you. A“waiting” response of 2is better.
The raise to 3is positive, typically showing at least two working cards (two kings, for example) or one working card plus a side-suit singleton.
A jump raise to 4is weak, denying an ace, a king or a singleton.
With an in-between raise, hedge by bidding 2NT and then bid spades. North-South were using Key Card Blackwood. In this version of responses, much like regular Blackwood responses, the king of the agreed suit counts as an ace, thus the 5response.
Nowadays, most play Roman Keycard Blackwood (RKCB). In this version, both the king and queen of the agreed suit can be shown.
Play commentary: As South, you have a heart loser with a diamond finesse available as a last resort. What other chances are there?
Do you see that “beautiful” 5-card heart suit staring you in the face?
It’s your salvation. If hearts are divided a civilized 4-3 (nearly 63%), you have the dummy entries to establish dummy’s fifth heart for a diamond discard! No diamond finesse will be needed. First, long-suit establishment and if that doesn’t work, fall back on a finesse is the normal order of business.
Play commentary 2: Win the A, retaining the K as a later dummy entry, and lead a heart (key play). Say East wins and returns a diamond to your ace. Cross to the 8, ruff a heart high, back to the 9, and ruff another heart high.
Assuming the opponents have each followed to three rounds of hearts, one high heart remains at large. You are counting hearts, of course. Say you are even if you aren’t! Cross to the K and ruff a third heart setting up dummy’s last heart.
Enter dummy with the K and discard your losing diamond on that tiny fifth heart you have worked so hard to set up. The trick to long-suit establishment is to start the long suit early while dummy still has side-suit and trump entries.