Discovered attack.

1.e4 e6 2.d4 d5 3.Nc3 Bb4 4.Nge2 dxe4 5.a3 Bxc3+ 6.Nxc3 f5 7.f3 exf3 8.Qxf3 Qxd4 9.Qg3 Nf6 10.Qxg7 Qe5+ 11.Be2 Rg8 12.Qh6 Rg6 13.Qh4 Bd7 14.Bg5 Bc6 15.0-0-0 Bxg2 16.Rhe1 Be4 17.Bh5


Its black's turn. Taking the bishop 17....Nxh5 is a bad idea. WHY?

Highlight in between bracket for answer:
[18.Rd8+ Kf7 19.Qxh5 Qg7 [if 19...Kg7 20.Nxe4 fxe4 21.Bh6+ Kf6 22.Rf8+ Ke7 23.Qxe5] 20.Nxe4 fxe4 21.Rf1+ 1-0]