Erwin, who had previously worked on The Lieutenant with Roddenberry, was commissioned to produce a treatment; an outline featuring a salt-devouring vampire was handed in on April 8, 1966. Meanwhile, George Clayton Johnson had been assigned a storyline, tentatively titled "Chicago II", in which the crew of the Enterprise visit a planet where the culture was that of 1920s mob-era Chicago, which later evolved into "A Piece of the Action". Johnson was hired after story editor John D. F. Black recommended him to the producers. Johnson decided to use the 1953 science fiction novel The Syndic by Cyril M. Kornbluth as the basis for the story. Roddenberry felt that Johnson's treatment did not match his vision for Star Trek, but did not want to lose him entirely, and asked him to write "The Man Trap". Erwin was paid in full for his version, and given a separate "kill fee" because it would not be used. Roddenberry wanted to see more action, so the creature's ability to create apparitions was added to the script from the original pitch. Stan Robertson at NBC suggested to Roddenberry that they might wish to get medical advice over whether the draining of a chemical from a person would kill them instantly. To find out, Roddenberry asked Kellam de Forest Research, who said that, while it had never happened in reality, a quick death would be likely. Johnson suggested that the creature in "The Man Trap" could be the last of its species. He compared its situation to the reduction in numbers of American bison. Roddenberry found the idea intriguing. Erwin was paid a further fee to terminate his contract, and Johnson wrote a first draft teleplay titled "Damsel With a Dulcimer." While writing, Johnson consulted Black, who advised him to place the creature on the Enterprise quickly to increase the pace of the episode. This draft was delivered on May 23, but NBC felt that hallucinations were being overused; the same plot device had appeared in the pilot episode "The Cage". Johnson wrote a further draft on May 31, which reduced the number of apparitions, and was well received by Robert H. Justman. Roddenberry and Justman made further tweaks; one was to restore the name "The Man Trap" from Erwin's original treatment, another removed a scene which introduced McCoy's apprehension when using the transporter. Johnson further edited the script, but complained about the change in