Solution
1. Qxe4!
White realised he can safely capture the black knight and rely on the X-ray effect of the c1-rook to defend the back-rank.
1. Qxe4 Qd1+ 2. Qe1
Note that 1. Qxe4 Qd1+ 2. Rxd1?? Rxd1+ and white loses.
Exercise #80
1. Qxe4!
White realised he can safely capture the black knight and rely on the X-ray effect of the c1-rook to defend the back-rank.
1. Qxe4 Qd1+ 2. Qe1
Note that 1. Qxe4 Qd1+ 2. Rxd1?? Rxd1+ and white loses.