This is aHand:

Bidding

We have no problem opening 2NT with 21 points (and a 4∙4∙2∙3 shape) after three Passes.

We have seen before how, when we find out partner's major is Spades, we can correct to a 4♠ contract. Here, North applies 3♣ Stayman and then goes on to 3NT over our 3♥ response. Well, we simply have to correct to 4♠ as North either has a four-card Spade suit or has wandered into the card room from a local institution.

Play.

You'd think with 26 points between us that 4♠ would be a cakewalk. Nope. The opening lead gives us pause for thought; it could be a doubleton (although leading from ♣9x is neither attractive nor advisable) or it could be a singleton. If the latter then we need to play with care.

We try covering the ♣9 with the ♣10 to see if East will play his ♣J and set up the long suit. East, though, has played the game before (he didn't come down in the last rain shower) and he plays low. Now what?

We start out with the ♠A, the ♥A and one Diamond as our losers. It's going to be almost impossible to prevent the defense from taking a Club ruff, so we need to be a little more sophisticated in our thinking.

What if we attack the Hearts first? In order to make this contract we have to find West with one of the Aces (if East has two entries and four Clubs we can't avoid losing four tricks) and we need to set up a winning Heart to take our Diamond loser. This we must do before we lose our Diamond stopper.

So, at trick two, we lead a low Heart to dummy's ♥Q. When it holds, we know West has the ♥A. Had East produced the ♥A and given West a Club ruff we would have had to hope that West had the ♠A.

Anyway... we continue the Hearts, letting West win. He can't return anything that hurts us. When he leads a Diamond, we make the move that can save us. We play the ♥K and discard a Diamond from dummy. If either of the opponents trumps in, we're toast. But they don't and now we can play on trumps forcing out the ♠A. East gives West a Club ruff (we are powerless to prevent that) but now the hand is effectively over. 

We then ruff our Diamond loser and take the rest of our winners.

That was a lot of hard work, but a fantastic glimpse of winning strategy. We were going to accept a Diamond loser, but knowing that there's no way to avoid a Club ruff, we had to take some risks to get rid of the Diamond loser. Cool beans.