Mate in 5
First,white watchs for back-rank mate by Bg6 and Ng5. 1.Bg6 Note that this move takes not only f7 and h7 but also g7 away from black King. 1.Ng5 fails by 1...g6. 1...hxg6 otherwise 2.Ng5 and 3.Re8 mate. 2.Ng5 fxg5 otherwise 3.Re8 mate.
3.Re8+ Kh7 4.Kg4! Zugzwang. 4...Kh6 5.Rh8 mate (C.McRae)