Really great episode - can take a while to get going, and the level of action is perhaps overly ambitious, but the fantastic soundtrack, constantly developing intrigue and general vibe of the episode gives it this sort of mature subterfuge vibe that you don't really see elsewhere in the show. Pertwee's Doctor is commonly compared to James Bond - and nowhere is that more evident than in this episode. Genuinely a great time, all things considered - though I do wish Liz got more to do.