The bidding: East does not have two and a half quick tricks but it is still a reasonable opening of one spade nonetheless. South has a one no trump overcall with 15 high card points and three spade stoppers. Axx is the minimum spade holding to overcall one no trump, so three stoppers is very good.
Stayman and transfers are still on, so North uses Stayman to find their four-four heart fit.
The fact that South does not initially double one spade does not deny four hearts. South just opted for the more descriptive bid of one no trump.
The contract: Four hearts by South
The opening lead: The seven of spades or the two if you like
I like to play the lead of a small card suggests an honour and the lead of a high card is top of nothing. If you lead the seven then the two, partner will know you have a doubleton because you should play top down. However, if you play the seven then the five, partner may not know if you have two or three. Partner should be able to figure it out, otherwise lead the two from three small cards.
The play: The declarer wins the opening lead and considers the trump holding. There will always be at least one trump loser because six of the declarer’s eight heart cards are small.
Therefore, he will take the safety play and cash the ace to catch a singleton king. It does not fall. Now he has to lead up to the queen of hearts.
Declarer, seeing that two diamonds can never be pitched and that an opponent may be short in clubs, takes the diamond finesse. It loses. East plays a spade and declarer, as before, plays just high enough to win. If clubs gave enough pitches, the diamond finesse would not be taken and declarer would just play hearts from his hand. Playing the ace and then a small heart works here.
Declarer goes to dummy on the ace of diamonds and plays a small heart. He ducks and the king wins. He wins the spade return, pulls the last trump and claims.
The result: Four hearts making four for +420.
Note: Knowing the location of the ace of clubs would help with the guess on the hearts but East would win the ace and return his last club. Now when West gets in with the king of hearts, East would get a club ruff. It is best to avoid clubs until trump are drawn.