Movie #5 : page 2

A count of south's points tells you that declarer must hold the ♦K along with the known cards — three aces and the spade queen.  A count of the tricks yields three clubs, two diamonds, three spades with a repeat of the finesse, and three hearts.  Partner's play of the ♥9 at trick one is a simple defensive convention that guarantees possession of the pertinent missing cards in the suit — namely, the J109; otherwise, there is no reason to overplay partner's spot-card.

That makes eleven tricks.  If declarer has the ♦J, a run of the club and heart winners would squeeze you in the pointed suits.  The only hope is that partner holds that card, in which case you can guarantee a defeat of the contract by leading a diamond honor!  The ♦10 is best, because it is less confusing to partner and helps him to count the tricks as well.

If you do not return a diamond, your comely opponent can arrange to cash the club ace (it doesn't matter whether she started with three clubs or four), lead a spade to the jack, and play off the major-suit winners to this elegant matrix:

Now the lead of the club king squeezes both defenders out of their diamond stopper.  Would the play actually have gone that way?  Unknown.  So many declarers have a built-in aversion to orchestrating these sorts of wonderful end-positions, although sometimes it is just a matter of going through the motions.

Lead a round suit, and win her affection; lead a high diamond, and win your section.