One of the Telos novellas whose quality was sometimes a bit variable, this one with the Seventh Doctor and Ace separately in a city with a timewarp and a deep hidden secret. It's had some positive reviews but pretty much bounced off me; I've liked other work by Dave Stone, but won't be recommending this other than to completists.
This was the next in the sequence of unread Seventh Doctor novels and novellas on my list after
Relative Dementias. Next in line is an early Past Doctor Adventure, Illegal Alien by Mike Tucker and Robert Perry