Completing the Fifth Doctor mini-series that began with Cobwebs and The Whispering Forest, here comes The Cradle of the Snake by Marc Platt and directed by Barnaby Edwards.
Tegan has been possessed (again) by the evil snake spirit the Mara (again). In order to save her the Tardis crew travel to the planet Manusa but when the Doctor drives the snake out of Tegan's mind it enters his brain. Have they unintentionally unleashed the evil that will go on to destroy Manusa?
I'm not familiar with the Mara from the TV show, and I should be. However the idea of a malevolent psychic force that can infect other brains is a familiar one from science fiction writing and this is a pretty good variant on that theme. There's some fun and suspense to be had from not knowing quite who is possessed at any one time, and having the Doctor as the bad guy is a nice twist which allows Peter Davison to do some convincingly evil acting.
Sarah Sutton, Mark Strickson and Janet Fielding are all pretty good here, and it certainly sounds like they have fun together if the CD extras are to be believed. Strangely there isn't a full cast list on the Big Finish page but the other characters were all fine as well.
It wasn't quite as exciting as The Whispering Forest but at least an audio drama saves us from a dodgy giant snake special effect. 3.5 out of 5 snake tattoos.