1.axb4! - Pseudo-threat: 2.Sxc4+ Kd5 3.Sf4#,2...Kf5 3.g4#,

1...g5 2.Bh6 g4,gxh4 3.Bf4#,

1...gxh5 2.Bc6 b5 3.f4#.

Rybinsk theme.