"The Hidden Planet" by Malcolm Hulke was commissioned in December 1963 and at one point was to be the fourth serial and then later the fifth serial of Series 1 after the insertion of "The Edge of Destruction" into the production block. It would further be deferred in January 1964 when it was realised that substantial rewrites would need to be undertaken. The story would have concerned a planet in an orbit opposite Earth's, with a parallel but in some ways opposite society to ours; for example, women were to be the dominant sex and all clovers would have four leaves. The original script was sent back for rewrites, and due to a pay dispute the rewrites were not made until after Susan had left the series; this necessitated further rewriting. A third submission was similarly rejected as Ian and Barbara were due to leave, and the script was dropped. The story was the subject of an April Fool's Day prank in 1983, when "Doctor Who Magazine" issue 76 claimed that one episode had in fact been filmed and rediscovered, and would be integrated into a twentieth anniversary special co-starring the Fifth Doctor entitled "The Phoenix Rises".