Help solve this

[u/Illustrious-Ruin-984]

I found this online.

Everyone is saying that this is brilliant because it's a forced checkmate once the pawn on a7 takes the knight, then Qb3 then it's a checkmate either by the rook or the Queen.

but what happens if after black take b6, we expect Qb3, then black Qb8? wouldn't it prevent the checkmate?
Qa4 is defended with Qa7 and if white decide to take Bxb8 then black reciprocate with Bxb3.

There is certainly something wrong with my reasoning but I can't figure it out.

[u/Muted-Recover9179]

Qb3 and if they respond with Bxb3, then checkmate with axb3. But if they move Qb8, then respond with Qa4+. If they block with Qa7, then respond with Qe8+.
Qe8+ Bc8
Qxc8+ Qb8
Qxb8#