The Doctor, along with Jamie and Zoe, lands on an unidentified planet. Initially, they think they have landed in the middle of World War I, but soon discover that they are actually in one of several War Zones controlled by the War Lords. These War Lords have abducted numerous human soldiers to create the most formidable army the universe has ever known. Leading this scheme is the War Chief, a fellow renegade Time Lord akin to the Doctor. As the situation unfolds, it becomes clear that the Doctor cannot tackle this challenge by himself, and his era of roaming might be drawing to a close.