The Sunday Puzzle
This position is from a game played in the seventies, namely Liddel-Silman (i.e. Jeremey Silman, famous chess author), San Diego, Black to move.
There is a crushing move for Black here. Can you find it (without the aid of a computer!)?
I messed it up totally, seeing that 1...Bd7 threatened a checkmate which can only be stopped by 2.Bf1, I thought the White bishop was simply overloaded, and chose the poor 1...Nxe4. I saw 2.Bxf4, but didn't see that after 2 ... Bd7, 3. Bf1 had everything covered, and then my (Black) king looks exposed to White attack. Annoyed with myself, I checked the winning line which is elegant. I must admit, I simply missed the point of the tactic behind the first move of the correct line which, when you do see it, makes calculation easier.
If 2. hxg4, Qxg4 and the threats, as Kevin pointed out, are unstoppable. First off, checkmate is threatened by 3...Qh4#. White cannot avoid this and save the Bishop. This was the key line to see - the rest is much easier.
If 2. Kh1 then f2! The pawn thrust finishes White off because if the White rook moves then either it allows the pawn to promote, or the Bishop is lost.