
1… Be2! is a fork that threatens Bxd1, as well as Bxf3+, winning material either way.
The point is that white cannot capture the black bishop on e2 since black will play Rxe2, pinning the white queen to the king.
Solution

1… Be2! is a fork that threatens Bxd1, as well as Bxf3+, winning material either way.
The point is that white cannot capture the black bishop on e2 since black will play Rxe2, pinning the white queen to the king.