A very nice problem! Of course, the first thought is going to be to take at h5 to double attack the knight which can't be protected by the queen:

1.Nh5? Qf3! 2.Rg7 Ke6 and now what does white do about the knight on h5? Alternatively, white can't capture the knight on g7 with Nxg7 at move 2 because of the threat Qe2+ and sure draw by repetition. However, if white plays......

1.hg5! fg5 2.Nh5 Qf3 3.Rg7! Ke6 4.Rg5 is now possible to preserve the material edge. this should be won for white.