Santa Rosa sectional 3/27

My favorite hand from the Swiss

You have Qx AJ9 AKxx AQ9x

You open 2N, partner transfers to 3S, then rebids 3N.

The lead is the HK.

KJT9x Tx x JT87x
Qx AJ9 AKxx AQ9x

In my very limited experience (about 3 hands over 2 years), hands like this that have a great 5 card suit but are very weak elsewhere should play in 4M. Otherwise, it's very likely the suit gets lost. Still, 3N on this hand is nearly cold. How do you play?

2 hearts and 2 diamonds are certain. The defense will give you a second heart trick in an attempt to establish their suit. We could bring in 4 spade tricks, but opponents won't be so obliging to win the first round of spades. After 2 spades, they win and knock out your final heart stopper, and you have no way to reach dummy without losing a club. Focusing on taking 4 club tricks leads to a similar problem.

I thought for a while and found a great solution: steal a spade, then work on clubs! They can't take the first spade, so you have 4 red, 1 spade, and you can ensure 4 club tricks!

Accordingly, I ran the SQ. It held. Then I cashed the CA, just in case the CK was singleton. LHO showed out (!).

So now they can hold up the proper amount of times in each suit. Changing gears again, I play a second spade, knocking out RHO's SA. I can force an entry in clubs because of dummy's great spots. RHO tables a heart after winning the spade; LHO could duck to preserve communications, but she wins and knocks out my final heart stopper. Since RHO has the CK, he has no hearts left. I end up taking 4 spades, 2 hearts, 2 diamonds, and 2 clubs.

I think I had the right idea, but missed the details. If we steal a spade by playing a low spade to the JACK, we're in dummy to finesse clubs! This will work as long as spades are no worse than 4-2, since dummy has the S9 (nice card) to solidify our spade suit. If they win the first round of spades, we can overtake the SQ.

Edit: I showed this hand to a friend, and we can ensure the contract by running the SQ, and then exiting a small club. If RHO ducks the club, we can finesse the club repeatedly now for 9 tricks. This works whenever clubs aren't 4-0 with LHO. I don't think there is a 100% play then.