Sometimes, misplays don't cost you. Here's one (click on "lakshmanok" in the hand diagram to hide the other hands and click "next" to follow the action")
After a straight-forward 2/1 auction and checking for aces and kings, partner puts me in the grand slam.
It seems to be a straight-forward guess for the queen of diamonds.
I play out the hearts and clubs and learn that East started with four hearts and two clubs. His lead of the 9 without the 8 seems to indicate that he has two spades, so he must have all five remaining diamonds.
I have misplayed the hand. I should have ruffed my club loser before pulling hearts to cater to the 5-0 diamond distribution. Resigned, I play my King of diamonds and to my shock, west plays the queen underneath! The grand slam contract was cold all along. Of course, if East had four spades, I would played him for the diamond queen (3-2 odds) and gone one down.
p.s. my first grand slam (as declarer) as far as I can remember ... most of my regular partners don't bid grand unless they can count 13 tricks.