Mate in 5 Exercise 18

White plays and wins in 5 moves https://lichess.org/J69MJ4Ie

1. Bf5+ Kb8 2. Nc5 Ka8 3. Bd7 Kb8 4. Na6+ Ka8 5. Bc6#

The analysis board does checkmate in 5 moves

1. Be8 Kb8 2. Bd7 Ka8 3. Nc5 Kb8 4. Na6+ Ka8 5. Bc6#

Source:

https://www.amazon.com/Chess-Puzzles-Advanced-Expert-Level/dp/B0917YQZP1