Viewing the whole board (a recollection)

Remember when i posted sometime back about viewing the whole board (see here) (and here)? If not, just think of it as another nice little puzzle to solve. I allready gave you the theme. It is up to you to find the answer. Black to move. Mate in 4.

Highlight between brackets to see solution (hat tip Mark's "Chess Training" for providing this nifty solution to include solutions without actually showing them ;-)
[1...h2+ 2.Kxh2 Rb8 3.a6 Rh8+ 4.Kg1 Rh1#]