Heard: Black Orchid by Terence Dudley, 1987? (print), 2008 by AudioGO (or BC).
Novelization of a multi episode arc featuring one of the Doctor Whos. I don't give a rat's ass which actor it was. Read by Michael Cochrane who looks to have also starred in those episodes.
The Doctor and his three companions land in 1925 rural England. Mistaken as a last minute fil-in for a local cricket game, the Doctor enthusiastically joins the game at a local estate. The Doctor does all sorts of cricketry and sets a record and impresses everyone. The Australian companion, Tegan, is thrilled with the game and has to explain the confusing rules to the other two companions.
Meanwhile, and slightly beforehand, a mysterious creature/person in the manor house has killed his male nurse and threateningly hovered over Ann, the Lady Cranleigh's soon-to-be daughter-in-law. Ann had been engaged to a different son who disappeared when exploring the Orinoco River in South America. Ann is now engaged to other second Cranleigh.
The Doctor leads his cricket side to victory and is invited to stay at the manor and join fancy dress arty. Apparently, fancy dress means costume party. Companion Nyssa is found to be identical to Ann and everyone stairs at Nyssa in surprise.
The mysterious creature/person slinks along hidden passages and priest holes in the manor house. While the Doctor explores the hidden passages the mysterious creature dons the Doctor's costume, joins the party and takes Ann away. The creature murders a servant when whisking the woman away.
The Doctor is suspected of the servant's murder. Lady Cranleigh and a mysterious South American Indian, who was helping care for the creature/person recover Ann. The Doctor is taken into custody. The Doctor introduces a couple cops to the Tardis. The Doctor and co. take a Tardis trip back to the manor and rescue Nyssa from the creature/person. The creature/person takes a diver off the manor roof.
1. Fun to listen to but nothing spectacular.
2. The novel is much more fleshed out than the TV version. I can tell without having seen the show. Information on commentary on the importance of manners to the Doctor, his pride, his curiosity. Fealty by servants to gentry that still existed in 1925. The novelty of mixed cocktail drinks in 1925.