Start by examining every check. There is only one: Ra8+. Black must defend himself. He has no way to capture the rook and can’t move his king because both of its flight squares are attacked by White’s knight. All that’s left is to interpose his bishop at d8. Now what next for White? Look for another check. Again there is just one: RxB+. If Black responds with KxR the board looks even simpler than it did at the beginning: Black rook at h8; Black king on d8; White knight on e5. The fork at f7 is self-evident.