Nocturne was the home planet of the Foucoo, and was one of the Doctor's favourite planets in the universe. It was located three parsecs from Earth, "smack in the middle" between the systems of Tau Ceti and Zeta Reticuli, and was a stopping-off point for those resting or fallen in humanity's war with the Foucoo. Glasst City was a major population centre on the planet, with canals and great granite mausoleum-like buildings.

The Fifth Doctor once visited Nocturne with Tegan Jovanka, which he later described as a "particularly lively visit," and the Seventh Doctor later visited Nocturne on at least two occasions: first with Melanie Bush, and then with Ace and Hex. (AUDIO: Nocturne)