The Spider's Web

"New Ways" is the fourth episode in the ninth season of Doctor Who, set on the planet of Kadralla in the future.

Synopsis
"Kadralla was great, it was brilliant, till you came and ransacked it!" - The Doctor to Zadar

The Doctor rendezvous with Billy, and they return to the TARDIS. En route to 16th century France, the TARDIS malfunctions and lands on the planet of Kadralla, where a once great civilization stood. The Doctor seems familiar with the lost people and their history, and soon discovers a sinister evil lurks on the planet, waiting to ensnare him.

Zadar
Zadar is a shadow-entity; a greater shade of the Shadow Halls. He has lived for centuries, and destroyed the civilization on Kadralla when they denied him as a new god. When the Doctor and Billy confront him, the Doctor blames him for several other similar incidents, but Zadar defends himself, saying that “they were pacified, not destroyed”. The Doctor warns Zadar that if he does not leave he will destroy him, but Zadar says there is no point in the Doctor defending Kadralla as it is lost. However the Doctor discovers hidden tombs where the last line of Kadrallans have lingered for centuries, and they use their combined power to banish Zadar. Before he leaves the Doctor orders them to never use such a power again, and to rebuild Kadralla.