As the Fifteenth Doctor, portrayed by Ncuti Gatwa, embarks on his inaugural epic journey aboard the TARDIS, he will be accompanied by Ruby Sunday, depicted by Millie Gibson, as she introduces herself as the Doctor's new companion. This episode features the Doctor confronting the legendary and enigmatic goblins as his path intertwines with Ruby Sunday, portrayed by Millie Gibson. Little is known about Ruby Sunday, who was left on Christmas Eve as an infant. Currently living with her mother, Carla, and grandmother, Cherry, her life is about to take a dramatic turn when she crosses paths with the Doctor, embarking on their first adventure together.