A big penalty we collected

Dlr: S Vul: N/S KQ10875 AQ 105 865 J62 KJ732 KQ J43 void 1098 AJ863 A10942 A943 654 9742 KQ

I sat South, and after two passes, partner opened TWO SPADES VUL, RHO bid TWO NOTRUMP alerted as minors, I raised to a mere THREE SPADES , and after two passes RHO, perhaps tempted by the "favorable" vulnerability bids FOUR DIAMONDS. I am tempted to whack this, but I pass, and LHO bids FIVE DIAMONDS which I DOUBLE when it comes around.

Now join me to see what befalls poor declarer in the East seat.
I get off to a trump lead won in dummy with the Q. A club is finessed next, and I win the nine with the King. I begin forcing declarer with Ace of spades, he ruffs. He next crosses to the Diamond King, and judges to finesse in clubs, alas I win with my now stiff CQ. I play a heart through the KJxxx, Partner cashes two hearts. Partner now continues the force and declarer is getting tapped out as he ruffs with the DJ. The position is now:

Dlr: S Vul: N/S Q1075 none none 6 J KJ7 none J none 10 A A42 94 6 97 none

RHO tried for a even trump break (too optimistic) and cashed DA, and was now completely out of control. even now he could have at least taken one heart trick for -1100, but tried to cash CA instead, and the roof fell in as I ruffed and led a spade for partner to take all the remaining tricks.
For -1400 (6 down)

Declarer from the start could have done a lot better by taking a better view in clubs.