...these 2 Knights (on dark squares) cover light squares nearby: a4, b5, c4, c6, d3, d5, d7. Therefore, Q moves to a dark square, without leaving the d-file, 1. Qd8 (out of danger from BK).
1...K moves, to the one square available, b4. But, but, but -- that's threatening c3N!! It's okay, after Q's next move, it won't matter!
2. Qb8+...K×c3 (if Ka5, Qb5#, if Ka3, Qb2#) 3. Qb2#
1...K moves, to the one square available, b4.
But, but, but -- that's threatening c3N!!
It's okay, after Q's next move, it won't matter!
2. Qb8+...K×c3 (if Ka5, Qb5#, if Ka3, Qb2#)
3. Qb2#
WQ simply occupied dark squares.