Guards ! Guards !

My chess brain still manages to avoid seeing some things, particularly involving Knights..

Below, I saw the threat of a draw from White, and the fact the knight could stop it ( and therefore noted that the knight could not move, unless it gave check ).

What I did not see was that the Knight giving check and being captured, allowed the discovered attack on the Rook capture and subsequent mate...problem solved, if I had but seen it !

Black to play