This is a prime example of where doctor who was at at the time. Philip Hinchcliffe and Robert Holmes were now well into the reigns as producer and script editor and of course tom baker was well and truly making his stamp on the series. These leaders were bringing the series to another level which had already grown under the previous team of Barry Letts , Terrence dicks and Jon Pertwee. Doctor who now was more than a children's show , it was prime time family viewing. Different camera angles were being used, the dialogue was sharper, the atmosphere was horrific and the acting was first class. There are great performances from Tom baker , Liz Sladen, Bernard archard , Michael sheard and Gabriel Wolfe in particular who all understood the premise of the series, and the tension that was needed for this story. This is paddy Russel's best story as director. The story was directed with pace and the scariness comes out in droves. The cliffhangers are amongst the scariest and horrific ever in doctor, the first episode cliffhanger really packing a punch , even though it was a villain getting killed , what a cliffhanger. Costumes and sets are all good and the location filming of what was then Mick Jagger's house was excellent too. Certainly one of the best voices ever in doctor who was sutech astoundingly played by Gabriel Wolfe . Top notch who this from a top notch era . Doctor who never bettered from this period *****