# Justifying a redouble

This puzzle is derived from a real game of bridge I played on Bridge Base Online.

I was sitting North on board 9 (N dealer, E-W vulnerable) and the bidding turned out like this:

West North East South
P 2♣ P
2♢ P 5♣ P
6♣ X XX P
P P

East as declarer won the first seven tricks and reached this position with the lead in his hand (obviously he would not know about NS's exact holdings in-game):

      ♠ AT
♡ K643
♢ -
♣ -

♠ J9     N
♡ Q7           ♠ K
♢ AJ W       E ♡ AT8
♣ -            ♢ 6
S     ♣ 7

♠ Q85
♡ J95
♢ -
♣ -


He ended up down one and my side bagged 400 points. However, given that I last played the ♠4, there was a justifiable line of play that would allow him to make the contract against best defence.

How can East make his redoubled 6♣?

There is no one set of exact card plays that works for all situations. What the defenders play has to be taken into account!

East should

Cash the last trump discarding the 9 of Spades, then cash two diamonds, discarding the 8 of Hearts. This brings everyone down to three cards. North has no winning defence.

This is because

North must keep the Ace of spades to prevent East winning the King. North must also keep Kx in Hearts to prevent East winning the AQ of Hearts. But then East leads the King of spades, forcing North to win and lead away from the K of Hearts.

• This is not a complete answer. For one, which heart should be discarded? Commented Sep 16, 2023 at 16:10
• I have updated my answer Commented Sep 17, 2023 at 5:53
• The continuation after cashing three depends on what North (i.e. me) discards during those three tricks too. There is no one set of exact card plays that works for all situations. Commented Sep 17, 2023 at 13:38
• Interesting that (with open cards) starting with diamonds almost works. Only if south dumps his queen (and another spade, and north 2 hearts) this fails Commented Sep 17, 2023 at 13:48

Here is the intended solution:

East plays his last trump, discarding the ♠9, then cashes the two diamonds in dummy. He has to note what I (North) discard on these tricks, for East's discard on the second diamond trick depends on it: the stiff and vulnerable ♠K if I discarded ♠10, the ♡8 otherwise (i.e. if I discarded a heart on all three tricks).

In this way I am squeezed. If I discarded ♠10 declarer now leads ♠J from dummy to endplay me; I have to lead a heart and the ♡A and ♡Q can be won. If I discarded hearts all along he leads ♡7 instead, forcing out my now-stiff ♡K and winning the tenace as before.