the TARDIS. After they leave, the planet explodes, killing the Drahvins. In the TARDIS, Vicki identifies a planet on the scanner. On the planet, an astronaut (Barry Jackson) wakes up in an alien jungle, repeating the phrase "I must kill". Production Conception and writing Schoolteacher-turned-screenwriter William Emms, a science-fiction fan and avid Doctor Who viewer since its beginning in 1963, submitted an unsolicited story idea to producer Verity Lambert and story editor Dennis Spooner in early 1965. His idea was to show two conflicting races—one beautiful and one ugly—and flip convention by making the beautiful race evil. Spooner commissioned Emms to write the serial, then named Doctor Who and the Chumblies on 1 March 1965, with a script due date set for 15 April. In mid-April, Spooner's successor Donald Tosh began working on Doctor Who, and handled the bulk of the rewrites for Emm's scripts; Spooner departed in mid-May. Emms disliked the amendments, which had included the reduction of four main cast members to three, and replacing the role of Barbara Wright—who had departed in the previous season—with Steven, which he felt made little sense as Steven was a trained astronaut and would not allow himself to become trapped in an airlock. The show's cast were also unhappy with the script; Hartnell and O'Brien felt that the dialogue and behaviour were inconsistent with their characters, and Purves felt that his dialogue was not changed enough from the original script with Barbara. According to Emms, Hartnell's role on the show was threatened if he did not follow the script. Galaxy 4 was the penultimate serial of the show's second recording block, which had begun with the second season's The Rescue; alongside the following episode, "Mission to the Unknown", Galaxy 4 broadcast was pushed to open the show's third season. Although Lambert was credited as producer for Galaxy 4, her successor—John Wiles, who had joined the programme in early June 1965—was effectively responsible for the show during its production. Mervyn Pinfield—an experienced BBC figure who acted as the show's associate producer from its origins to January 1965—was originally assigned to direct Galaxy 4. Pinfield had most recently directed The Space Museum (1965), but was given a larger budget for Galaxy 4; he was also assigned to direct "Mission to the Unknown", effectively combining the two stories in a single five-week production block. Soon after production commenced, Pinfield's failing health prevented him from