In the book, the position originally had a rook instead of a queen. And notes that taking the rook leads black pinning white's queen, and a draw after black puts his king on h8.
In the original position, white could have won by playing Qf4+. Black can either block the check with the rook (Rg5) and then lose it to h4—or, he could move the king and lose the rook to Bxg8. Either way, white wins.
However, with a queen on g8, instead of a rook, white's Qf4+ no longer wins. Qg5 blocks the check and attacks white's queen.
Provide an assessment of the position, and prove with a variation involving what you find as best moves for both sides.