A thrilling and atmospheric adventure in the traditional Doctor Who mould. The story contains a little of everything that has always made Doctor Who successful: Suspense, action, humour, tragedy, it's all here, as is an occasionally unnecessary and lurid attention to gore which did sometimes seem out of place. The Zygons are exceptionally well developed here and we learn much more about them, their origins and characteristics in a convincing and attractive way. The Skarasen add to the story also, probably because in this case we can only imagine them! It was a shame Jago couldn't make an appearance but with dear old Litefoot well and truly on form his partner's absence was barely noticed.I did feel that the way the Doctor defeated the Zygons was rather extreme but hey, as we all know even the Doctor gets it wrong! Overall, one of the most satisfying and exciting adventures in the series .