Sontaran warriors set their sights on the Earth and its inhabitants.
Sunny and Bajie arrive at Pilgrim's Fortress, only to face an angry M.K. The Widow enlists Gaius. Moon and Lydia rally the troops.
Sunny and Bajie seek help from a reclusive former Master. The Widow must confront a spectre from her past as Chau's slave.
Sunny plays a dangerous game, causing his friends to question his loyalty. The Widow discovers the existence of a new weapon as her alliance falters.
