The most forcing line is 27…Qxh1+ 28 Rxh1 Rxh1 29. Kxh1 Rxa3 and Black is much better. The three pieces are much stronger than the queen and you have two extra pawns to boot. Unless white can break through quickly he is in trouble. The most natural try is 30. f5, but Nxd4 followed by Nxf5 refutes that.
Other interesting ideas include 1…Nxd4 or 1…Nxb4 or 1…Bxb4.
Bill Smythe