Solution
1.G*1a.
The bishop attacks 1a-square.
1.G*1a.
The bishop attacks 1a-square.
1.P6d 2.Px6d 3.P*6c. Black threatens P6b+ Gx6b S*7a.
If White plays 4.P7d, you can simply play 5.S6*b.
1.R*1a
The bishop attacks 1a-square.
1.S*1b 2.+Bx1b 3.R3a+ 4.Kx3a 5.G*3b.
1.N*2e
The king is stuck. Smothered mate.
1.R*1e
The bishop attacks 1e-square.