Ep 1. New Earth

In "New Earth," the second episode of Doctor Who's second season, the Tenth Doctor and his companion Rose Tyler travel to the distant future to visit the planet New Earth. The planet has been rebuilt following a devastating virus that was unleashed by the the villainous Lady Cassandra, who the Doctor encountered previously.

Upon arriving on New Earth, the Doctor and Rose discover that the planet is now being used as a giant hospital where thousands of different species of beings are being treated for every type of ailment imaginable. The hospital is run by a group of humanoid cat-nuns called the Sisters of Plenitude, who have the ability to cure people of even the most deadly diseases.

However, it soon becomes clear that the Sisters are not what they seem. The Doctor discovers that they are breeding sick patients in secret, in order to perfect their cures and treatments. Meanwhile, Rose comes face to face with a familiar face from the Doctor's past - Lady Cassandra herself, who has had her mind transferred into the body of one of the Sisters.

As the Doctor investigates the sinister goings-on at the hospital, he and Rose become separated, with the Doctor forced to team up with a group of rebel patients to uncover the truth about the Sisters. Together, they must face a dangerous new threat - swarms of infected patients that have mutated into deadly creatures.

"New Earth" is an action-packed episode that combines science fiction with horror and mystery. It explores themes of greed, betrayal, and redemption, as well as the importance of compassion and empathy. David Tennant and Billie Piper deliver strong performances as the Doctor and Rose, and the cat-nuns are a memorable addition to the Doctor Who universe.