'Matrix', written by Robert Perry and Mike Tucker, features the Seventh Doctor and Ace.
Back Cover Blurb
'I won't fight you,'
'Oh, but you will.' The voice twisted and cracked. Fury and madness tore through it. 'You will fight me, Doctor!'
The Doctor is on the run from a faceless enemy that knows his every though and move. he flees to his past, panning to leave Ace in sage hands in order to fight on alone. But his enemy has other plans, and the Doctor's history no longer exists.
The TARDIS is finally drawn to London in the winter of 1888, where the Doctor and Ace discover a dark secret from Gallifrey's past, and the name fo their unseen opponent.
It is Jack the Ripper