Red Dawn: The Fifth Doctor and Peri (unusual choice - obviously only one gap in the established narrative where this can take place) land in what turns out to be an Ice Warrior mausoleum on Mars, at the same time as an Earth probe comes to explore. Needless to say, disaster ensues, but the real monsters turn out to be the humans behind the earth exploration ship. Earnestly done by everyone, with particularly good audio evocation of the Ice Warriors and the Martian landscape. Good but not great.
The Spectre of Lanyon Moor: I felt this was a different matter, nearly as good as The Genocide Machine (so far my high point of the Big Finish series). The Doctor and Evelyn Smythe are investigating ancient artifacts in Cornwall; the retired military officer cleaning the finds has in fact an agenda of his own, and recognises his old friend's new face immediately. OK, the plot itself is a rip-off of any number of classic stories, including The Daemons and The Stones of Blood, but done with tremendous conviction by all.
Winter for the Adept: A rather peculiar tale of the Fifth Doctor and Nyssa dealing with poltergeists in a Swiss finishing school. The Doctor himself barely appears until the end of the first of the four short episodes, and almost everyone is putting on silly accents. Really not very convincing in the end.