I ran across the following mate-in-4 puzzle for white reading 1001 Chess Exercises for Beginners by Masetti and Messa and had a difficult time with the analysis.
As always, I encourage you to find the solution before reading on.
The discovered check move 1. c7+ forces black to take the bishop with his rook 1 … Rxf3, as there is no other moves available. When exploring this line, it was difficult to find what was next. Then, I stumbled upon 2. Qe8+. If 2 … Bxe8, then 3. c8=Q# is game over. So, instead, 2 … Rxe8. But , then we have the wonderful resource 3. Rxe8+. Again, same thing, if 3 … Bxe8, we have 4. c8=Q#. Is there anything black can do?
Yes. What if 3. Rxe8+ Kb7? While there is a winning path to checkmate with 4. c8=Q+, there isn’t a checkmate in 4 moves here. This is what made this so interesting to me.
So, instead of starting with the discovered check, let’s end with it!
1. Qe8+ Rxe8 [1 … Bxe8 2. c7+ Rxf3 3. c8=Q#] 2. Rxe8+ Bxe8 3. c7+ Rxf3 4. c8=Q#.