The eight-episode series will introduce Ncuti Gatwa as the Fifteenth Doctor, a new incarnation of the Doctor, an alien Time Lord who travels through time and space in the TARDIS, which appears to be a British police box on the outside. The series also introduces Millie Gibson as the Doctor's newest companion, Ruby Sunday. Filming began in December 2022, with production moving from Roath Lock Studios to Wolf Studios after Bad Wolf became a co-producer of the series.