The Doctor discovers that the alien is a Sontaran warrior called Linx.
Irongron is in a foul mood when a captured Sarah is brought before him. His mood improves when Linx presents him with a Robot Knight which is then put to the test on a captured Hal. The archer is only saved when the Doctor intervenes from afar, shooting the robot control box from Irongron’s hands. The ensuing confusion lets both Hal and Sarah flee, and they head for Wessex Castle. There, Sarah concocts a plan to kidnap the Doctor, who she thinks is working for Irongron rather than against him.
Meanwhile the Doctor has realized that Sarah is in the time period and has been captured. He finds Linx’s lab, where the kidnapped scientists have been hypnotized except for Rubeish. He is caught by Linx, who restrains him using a head device, but Rubeish frees him when Linx leaves. The Doctor then leaves to search for Sarah, but is chased by Irongron and his men. When the Doctor stumbles, Irongron raises his ax.