She and Radcliff were all that was left of their planet after it was obliterated by the Garvak posing as a human named Abel Crumpton. He had stolen the Egg of Abundance that contained the genetic imprint of Zantoran life, and it was Lettice and Radcliff's mission to retrieve it.
Lettice ran into Harry Sullivan and recruited him to help her retrieve the Egg. She was captured by Crumpton but was rescued by Harry and Radcliff. After switching the Egg for an egg, the three managed to destroy the Garvaks, and Lettice and Radcliff took the Egg to another world to seed it. (PROSE: The Man from DOCTO(R))