agb2002: White has a knight for a bishop.
Black thratens cxd4.
The pawn on g6 blocks the action of the white queen and the rook on g1. The black queen protects f4. Therefore, 24.Nf5+:
A) 24... gxf5 25.Qxf4+ Kh7 (25... Kh5 26.Rg5+ and mate next) 26.Ng5+
A.1) 26... Kh6 27.Qh4+ Kg7 (27... Kg6 28.Nh7+ Qg5 29.Rxg5#) 28.Ne6#.
A.2) 26... Kh8 27.Qh4+
A.2.a) 27... Kg7 28.Ne6#.
A.2.b) 27... Qh6 28.Nxf7+ Kh7 29.Nxh6 + - [Q+2P vs b+n].
A.2.c) 27... Nh6 28.Nxf7+ Kh7 (28... Qxf7 29.Qxh6+ Qh7 30.Qf6+ Qg7 31.Qxg7#) 29.Qxf6 and mate soon.
A.3) 26... Kg7 27.Qh4
A.3.a) 27... Kf8 28.Nh7+ wins decisive material.
A.3.b) 27... Nh6 28.Nh7+ as above.
A.3.c) 27... Qh6 28.Ne6+ Kh8 (28... Kh7 29.Rg7+) 29.Rxg8+ Kxg8 (29... Kh7 30.Rg7+; 29... Rxg8 30.Qxh6#) 30.Qxh6 Rxe6 (30... fxe6 31.f3 followed by Rg2 with a winning attack) 31.Qg5+ Rg6 32.Qxf5 + - [Q+2P vs r+b].
A.4) 26... Kg6 27.exf5+
A.4.a) 27... Qxf5 28.Nh7+ and White captures the black queen with check, not allowing Rxe2.
A.4.b) 27... Kh6 28.Qh4+ Kg7 29.Ne6#.
A.4.c) 27... Kg7 28.Rxe8 Rxe8 29.Ne4+ wins decisive material.
A.4.d) 27... Kh5 28.Qg4+ Kh6 as in A.4.c.
B) 24... Kh7 25.Ng5+ Kh8 (25... Qxg5 26.Qxg5 gxf5 27.Qg7#) 26.Qh4+ Nh6+ 27.Qxh6+ Kg8 28.Nh7
B.1) 28... Qh8 29.Rxg6+ fxg6 30.Qxg6+ Qg7 31.Qxg7#.
B.2) 28... Qe5 29.Rxg6+ fxg6 31.Qxg6+ Kh8 32.Nf6
B.2.a) 32... Re7 33.Qh6+ Rh7 34.Qxh7#.
B.2.b) 32... Qxf6 33.Qxf6+ Kg8(h7) 34.Qg7#.
B.2.c) 32... f3+ 33.Kh1 (33.Kg1 Rg8 - +) doesn't change anything (33... fxe2 34.Qg7(h6)#).