Thomas Fuller, an English curate, author and historian who died in 1661, said, "If thou art a master, be sometimes blind; if a servant, sometimes deaf."
If thou art a bridge player, be never deaf nor blind. Listen carefully to the auction and watch closely every card played.
In today's deal, South did not draw the logical conclusion from the auction. Look at his hand. He dealt and opened one spade, West overcalled one no-trump (strong), and North responded three diamonds. After East passed, what should South have done?
West's choice of overcall would not have appealed to everyone. It described the hand strength, but hid her five-card major.
North's three-diamond response described her hand well -- a good long suit and nothing else. (With a strong hand, she would have doubled for penalty.) South had no extra values and no good fit for diamonds, so he should have passed, reaching a contract that could have been made.
Three no-trump, though, had no chance. West, thinking that her partner had no points, led the heart two, which was theoretically fourth-highest. She purposely falsecarded.
South, thinking West had the spade ace and queen, won with his heart jack, played a diamond to dummy's jack, and led a club to his queen. West won and continued with the heart nine. South won and played another diamond, but West took her ace and cashed her three heart tricks. East discouraged in spades, and South also pitched two spades. Then West accurately exited with a club, leaving South stuck in his hand. The contract went down four.