A Curious Incident

 "What would you bid on this hand, Watson?" asked Holmes. "The auction begins (1C)-Pass-(Pass)-Dble-(2C)-2S-(Pass) to you. and you have the North hand below."

"I guess I would raise", replied Watson. "You have five-card support and a singleton which is more than you promised with your initial double."

Watson continued: "Is there any other point to which you would wish to draw my attention?
Holmes: "To the curious incident of South's One Spade overcall."
Watson; "But South did not overcall One Spade. He passed."
Holmes: "That was the curious incident."

So, if South had any more than the hand above, he would have overcalled One Spade, and you should pass 2S rather than invite. Strengthen the North hand slightly, making the king of diamonds the ace, and you are worth an invite. East will compete to 3C for sure, but then you might buy it in 3S on the next round.

The defence needed to be accurate. West led the jack of clubs and East played the two on this trick. Good pairs have an agreement that when a singleton appears in dummy in a suit contract, the third hand to play gives suit preference, a small card for the lower suit and a high card for the higher suit. If East had the king of hearts and not the ace of diamonds, he would play the seven of clubs on this trick, preference for hearts. East's two of clubs was preference for diamonds and the switch to the jack of diamonds defeated the contract for a good board for East-West.