Another wonderfully complex Sixie and Charley story, that ends with a cliffhanger!! I truly love this pairing, and the plot enacted here, in which a long-term TARDIS stowaway threatens to upset the balance of everything, and there are Daleks to boot. ( )

I keep on enjoying the Six/Charley plays despite my inclination, and Patient Zero was no exception. The Doctor is absolutely aware that Charley Pollard is much more than she has admitted; but Charley now finds herself substituted by a mysterious invisible alien which takes over her very being; meanwhile the Doctor is defending himself from the Viyrans (boo!) and Daleks (yay!). A great set-up for the next two stories. ( )