White plays and wins in 4 moves https://lichess.org/fg7BN7lB
- Nh5 Kh8 2. Kf7 Kh7 3. Nf6+ Kh6 4. Bf4#
The analysis board does checkmate in 5 moves
- Nf5 Kg8 2. Kg6 Kh8 3. Be7 Kg8 4. Nh6+ Kh8 5. Bf6#
Source:
https://www.amazon.com/Chess-Puzzles-Advanced-Expert-Level/dp/B0917YQZP1