Robot

Someone or something has been stealing top secret scientific plans and parts. With UNIT and Sarah Jane Smith investigating, it soon becomes clear that a group of scientists and an advanced robot are behind it all. Their plan: blackmail the world's superpowers using some stolen nuclear missile launch codes. Robot comes across as a typical Third Doctor story and yet it's clear right away that things have changed. Having traded his frilly shirts and Venusian aikido for an absurdly long scarf and a Cheshire Cat grin, the Fourth Doctor's chaotic whimsy lends the proceedings a burst of energy. And, at the end of the serial, as the Doctor, Sarah Jane and the newest companion Harry Sullivan board the TARDIS, Doctor Who effectively ends the UNIT era and the Doctor's Earthly exile.

Rating: You may be a Doctor, but I am the Doctor%