A good character piece of a story, with a nice mystery and a very insidious Dalek threat. It uses some of the same ideas as Dalek and the Witch's familiar, but manages to be distinct enough to be entertaining in its own right. The story is straightforward but effective, leaving room for the acting to shine. All secondary characters are compelling and keep you guessing whether there will be a secondary bad guy, as well as hoping there won't be. The Doctor and Constance are in good form, and Briggs gives a truly unhinged and creepy performance as the Dalek of the play. A good play, and notably a very good introduction for the Daleks if someone has never heard of them.

Note: the story alone would net 3.5 stars, I think it deserves 4 stars for the memorable performances.