Its black to play. Only move is Qxg5, followed by Nxf7 forking black's king and queen and its a win from there on.
The puzzle starts after Black's 11th move!
Nice combination, but it's a very known motif to keep in mind. Knights love queen and king on the same square color. When a bishop pins a queen, the queen has no other color option.
Also, interesting line if 12...Ke7 is 13.Qxc5+ Qd6 and the most material gain comes with N+ because the queen is pinned.
