White plays and wins in 3 moves https://lichess.org/lgp7GFJ9
- Be6 Rd1 2. Rg2 Rb1 3. Rg8#

The analysis board does checkmate in 5 moves
- Be2 Kg8 2. Rd8+ Kh7 3. Bd3+ Re4 4. Bxe4+ Kh6 5. Rh8#
Blacks could have delayed with a tower's check.
Source:

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