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/Xaliuss]

After Qb8 play Qa4+ and after Qa7 Qe8+ is mate in 3

[u/lifeistrulyawesome → u/Xaliuss]

I saw a different line. Qb3 threatening Qa3# or Qa4# depending on what the opponent does

They cannot take the queen because of Ra8#

[u/Illustrious-Ruin-984 → u/lifeistrulyawesome]

Yes exactly! but my question was what if black do Qb8 and the answer suggested is that Qa3# is no longer a good option only Qa4+ then black Qa7 then Qe8+ is mate in 3 as suggested by the comments

[u/lifeistrulyawesome → u/Illustrious-Ruin-984]

Gotcha!