Black's queen is en prise, and so is his a8-rook.
Such is the power of the double check, that White has no time to waste
thinking about offense!
1...Rc1+
Double-check.
2.Kxc1 <forced> Qc4+
3.Kd2 <forced> Qd3+ 4.Ke1
Which might as well be forced, since 4.Kc1 Qc2#.
4...Qe3+ 5.Kf1 <forced>
When your opponent's replies are forced, it much
easier to calculate seemingly long variations. The deception
lies in the lack of side branches in the analysis tree.
Now that the white king has been driven half-way
across the board, Black, with his next move, threatens White with yet
another double check!
5...Rf8 6.Kg2
6.Qd5+ Be6+
6...Qe2+ 7.Kg1 <forced>
Of White's first six moves, four of them are 100%
forced, and a fifth might as well be.
7...Be6
The threat of mate on f2 forces White to surrender his
forces merely to stave off the inevitable...
7...Qxd1+ also works: 8.Kg2 (8.Kf2 Bh3+ 9.Ke3 Qxd4+
10.Ke2 Rf2+ 11.Ke1 Qd2#) 8...Qe2+ 9.Kg1 Be6
8.Nf7 Bh3+ Qxd1+ 9.Kg2 Qe2+ 10.Kg1 Bh3
Now Black threatens mate on f1! Time for White
to call it a day, methinks. However, for the morbid amongst us
<conspiratorial smile>, here is the denouement:
11.Nh6+ gxh6
11...Kh8 12.Nf7+
12.Qd5+ Kg7 13.Qxe5+ Qxe5 14.dxe5 Rf1 mate.
