As Rose Tyler embarks upon her first big TARDIS adventure with the newly-regenerated Doctor, they discover a sinister hospital run by strange cat people and run in to two old acquaintances, The Face of Boe and Cassandra.The Doctor and Rose set out on their first adventure together since the Doctor regenerated. The Doctor takes Rose to see the Planet New Earth, colonized by the human race since the destruction of the original planet Earth. On arriving the Doctor receives an invitation to visit a hospital run by the sisters of plenitude. A sisterhood of cat-women nuns who have the uncanny ability to cure so many long thought incurable diseases. But as the Doctor and Rose discover there is a sinister method as to how the Sisterhood manage to develop such cures. While unknown to them both an old enemy thought to be deceased, awaits the Time lord and his companion.