Wooden Heart
Martha and the Doctor find themselves on the seemingly abandoned starship Castor, adrift in deep space. They soon discover they are not alone, as a strange wooded countryside and a fogbound village appear within the vessel. As they investigate the missing crew and the ship's power source, they uncover a village haunted by disappearances and a history of destruction.
The travelling Time Lord at the centre of the series, who moves through time and space in the TARDIS and changes appearance on regenerating.