1… Rc8! threatens Rc1+, Qd1, Rxd1# and proves that the white knight is overloaded since 2. Nxc8 allows Qxd5.
1… Rc8 2. Bd3 Rc1+ 3. Bf1 Qxe7 and black saved the rook and achieved a strong position
1… Rc8 2. Kf1 Qxd5 3. Nxd5 Rc1+ 4. Ke2 Rxb1