sentences:  However, due to sickness on the part of Emms, this took so long that further rewrites were needed to explain the loss of Ben and Polly, its place in the schedule was taken by "The Underwater Menace" and on 4 January 1967 the story was dropped.Emms reused elements of the story in "Mission to Venus", a Choose Your Own Adventure-style story featuring the Sixth Doctor.Written by Barry Letts, this story outline, submitted around November 1966 to story editor Gerry Davis, would involve a race of beings undergoing a cycle of mutations, akin to that of a butterfly, moving from one form to another via a chrysalis stage.