The Doctor urges Peto and Grissell to build a mental barrier between themselves and their host. In the square, the lions chase after Nyssa and Tegan; they kill seven civilians and a policeman in the process. Finally, the Sevakrill are forced out and the lions return to their plinths. The Doctor spends two weeks lowering the missile into a tunnel beneath the column and builds a floor over it. He leaves behind a short range sensor that will warn him should the missile ever be activated. He comments passingly that he might check to see if someone has tampered with Cleopatra's Needle.