Charles Darwin wrote, "It is not the strongest of the species that survives, nor the most intelligent, but the one most responsive to change."
However, you could argue that being responsive to change makes you not only a survivor, but also a strong and intelligent person.
Yesterday we started to look at the responsive double. If the player on your left opens with one of a suit, your partner makes a takeout double, and the responder raises, a double by you shows the values to bid, but no clear-cut bid available. You hope partner can do something intelligent.
You can also make a responsive double after your partner overcalls and responder raises opener's suit — as in today's deal. This responsive double is more clear-cut. You (North) promise length in the two unbid suits.
South rebids three clubs for want of anything better to do. (Note that East, with no extra spade length or high-card strength, should not bid three spades, where he would go down two, losing two hearts, a heart ruff, one diamond and two clubs.)
Against three clubs, West leads the spade four. The defenders take two tricks in the suit, then shift to a trump. But there is little to the play. Declarer gives up a diamond trick, wins the next trump lead, takes a diamond ruff in his hand, cashes the heart ace, ruffs a heart on the board, draws the last trump, and concedes a diamond. He loses two spades and two diamonds.
Without this version of the responsive double, how would you get to three clubs?