The answer is complicated but first we must look at 1...Rxh2?? threatening 2...Rh1# then white wins with 2 Qxf8+ Kxf8 3 Re8# so black has to play th remarkable 1...Qc4+ when the bishop is deflected from defending the key e8 square so after 2 Bxc4 comes 2...Rxh2 and the 2 Rh1# threat forces 2 Qxf8+ Kxf8 3 Re8+  Kxe8 4 Ke1 when 4 gxf6 wins for black-this was from an actual game played between Alex Bunyan and Frank Crowl in Sydney 1934.