This novel, by Justin Richards, was first published by BBC Books in 1998 and reprinted in 2013 as part of the 50th Anniversary Collection.
It features the Second Doctor, as played by Patrick Troughton, with his companions Jamie and Victoria.
The Doctor and his companions arrive in what they initially believe to be a medieval castle but is, in fact, a fortress built on an asteroid. At one time it was a defence post on the border of the Haddron Empire; now, with the empire having expanded it serves as a prison.
The travellers soon stumble over the body of a murdered man where they are discovered by the prison’s security forces.
Being rapidly cleared of involvement in the murder, the Doctor and his friends become involved in a story of politics, rebellion and civil war.
Although it doesn’t become obvious until halfway through, this is basically a ‘base under siege’ story which was very common during the Troughton era.
Richards succeeds in planting a picture of Troughton in your mind as you read. However, Jamie and Victoria are underused and have very little to do; they seem almost two dimensional.
The supporting characters are well drawn and you become involved in their story. A couple of deaths towards the end were a bit of a shock.
This is a story that could have been made for the tv series if they had had the budget.
As Dreams of Empire was originally published in 1998 it has a more adult feel than the recent New Series Adventures. Certainly, the violence is more graphic and sex and marital infidelity are suggested though there is nothing explicit.
Also the ideas behind the novel (and I would urge you to read the introduction) are more sophisticated than we would currently expect.
I would recommend this novel without hesitation.