A perfectly serviceable story to welcome Tom Baker to the role as Doctor. He gets given a classic Pertwee story off the bat with UNIT and evil scientists but deals with it with a completely different, breezy tone. Harry is fine here as an addition, and Sarah Jane gets some great journalist detective work early on. The idea of a robot struggling with emotions is a fine plot, but becomes obvious quick. The nuclear launch codes and the robot are both defeated with ease by the Doctor, so no great climax. A solid start all in all.