Interesting Fork
Oh man.. Ouch! lovely.
Very cool puzzle, got on the second try. My first idea, correct me if i'm wrong reaches a similiar position:
1. Qb5...Qxb5
2.Bxb5...Bc8-d7
3.Nd5-c8+...Kd8
4.Nxa1
Edit:
Oh wait, that actually loses the bishop. My mistake, nevermind.
The reason move 4 is not RG1 is as follows.
4 RG1, QxF3. 5. NxC7+, KD7 6. NxA8, BxF2+. 7. KF1, BH3+!
If white chooses 5. QxG8+, KD7. 6. QG3, BB4+. 7. KF1, QD1+!
With this line white gets a rook for free and removes the queens from the board, simplfying the end game.
