It was played at nine tables. At one South played in 3♣, but at the other eight South was in 3NT. Assume the bidding was 2NT - 3NT; there are no clues to the distribution. West led either ♥3 or ♥2, according to agreement.
You can see that EW can take the first five tricks, but not surprisingly that didn't happen at all tables. Five Souths made 3NT, one with an overtrick, when dummy played low at trick one and East put in the nine.
Of those Easts who played the king at trick one, one blocked the suit by returing the original fourth best 7. Two returned the 10, but one West played the eight (!) at trick three to undo all the good unblocking work.
Those who blocked the suit had the last laugh when East switched to a diamond to try to reach partner with the last heart and declarer took the finesse for two down.
Is there any guide to whether to play the nine or the king at trick one? Is it just a guess? I can see that one works when partner has led from Axxxx and the other when they've led from Jxxxx.