White’s hopes are bound up with perpetual check on the c8- and f5-squares. Consequently, Black needs to find a way to drive the white queen off this diagonal. In the game, Black missed a chance to end the game beautifully:

Having seen the winning idea, it is easy to find the right way of executing it: first, the white king is driven to a square where the black pawn will queen with check.

Winning.

If we look at the opposition of queens on the e-file from a more imaginative standpoint than the usual one, and note that even though the bishop on e5 is pinned, it can move anywhere, we soon find a nice finish:

And the game ends.

Any means by which White can get his queen to h4 or h5 are good. He finds a way:

27...Qxb8 28.Qxh4 and soon mate.

The final deflection. White resigned. After any capture, he is mated: 29.Qxe3 Qg2# or 29.Rxe3 Qf1+ 30.Bxf1 Rxf1#.

It seems that the knight has fallen on c8, because natural kinds of pressure on the bishop on c5 do not bring significant benefits. For example, 15.Rc1 can be met by 15...Nd7, with an uncertain struggle. However, if you connect your imagination, it is possible to find...