A perfectly fine but largely straight-forward story. The secret agent character was so stereotypical I thought the opening was part of a tv show the way it was handled. I think his arrogance was intentional as this is sort of a James Bond-esque story. Michael Troughton's Second Doctor is always fun, but was pretty unnecessary to the plot line here. It did advance our Zygon Century story (and couldn't resist ending with a title-drop and evil laughter) and connect in the previous two stories. Overall I'm positive on Zygon Century, that second story being the real standout.