 The episode ends with the Doctor showing Zoe his last encounter with  the Daleks, to warn her of the dangers ahead if she choose to join  the TARDIS. This was used to lead in to a repeat of the story "The  Evil of the Daleks" the following week. Together with narration over  the opening of that story, this uniquely tied the only repeat of a  Doctor Who story in the 1960s into the ongoing plot