I watched my partner and wife Charlene play this hand in a recent game at the club, and as each card was revealed, I came to the understanding that the heart suit was the key to the hand and that the position of the honors was classic. The opening lead of the heart jack, which promised leader also had the 10, told the north defender that the leader did not own the queen; since obviously it lay with the declarer, the key to the defense of the hand is that north must duck the opening lead. If he takes the king, the defense is ended because declarer now has two heart stoppers, but the heart winners in the south hand are stranded forever. North keeps getting into the lead but has no heart left to allow south to cash winners and defeat the contract. This position is explained in several texts on defense, so I presume the defenders either did not read about it or did not recognize the position.
Follow the alternative play if the north defender plays correctly: When declarer passes the heart jack to her queen, north must duck the king and allow the queen to capture the trick. Then when north is on lead with either the diamond ace or the spade king, the defender must then lead the king of hearts to the ace on the dummy, so that when she is in with her other winner, she will have a heart to lead to south, and the suit is unblocked. Now south can cash two hearts, to go with the spade king and diamond ace and jack or the club king to defeat the contract. I know that declarer could drop the club king, but that is an anti-percentage play, and east should take the club finesse every time.
One last note about the play: North should play the heart nine on the first trick to signal south to continue hearts if she should gain the lead, and in this case must still be aware enough to dump the king under the ace when hearts are continued.
Watch for this defensive situation because it does arise from time to time, and you will get a good board when you defend properly and defeat the contract.