Answer to What’s Going On No. 1
Assuming that partner has not missorted his hand (and has not taken leave of her/her senses), the only logical reason for partner to raise 5S to 6S is that pard has the 3 missing keycards. (Remember — 5C shows either 0 or 3 keycards.)
Further, you know partner’s shape. Partner chose to make a limit raise to 3S, rather than making a game-forcing bid (e.g., Jacoby 2N, a splinter, or even a 2 over 1 bid). That must mean that partner’s only points are the 3 missing keycards, and that his/her hand is flat as the proverbial pancake, i.e., something like:
This is an uncomfortable hand to bid — the AK/A combination is a big plus, but the 4333 shape is a potentially even bigger minus.
When you bid 4N, partner knows you have a slammish hand with 2 keycards (since you were apparently willing to go to 5S knowing that partner could have 0 keycards). Further, when you bid 5S, partner knows that you are assuming that partner has 0 keycards. Thus, partner raises you to 6S, to show that he/she has 3 keycards.
But that’s not the end of the story.
Knowing partner has something like 4333 distribution and the missing 3 keycards, you can see that the only way to go down in a spade grand slam is for RHO to ruff the opening lead.
Therefore, your only bid is 7S.
