When two belligerent Dominators and their robotic servant Quarks land on the peaceful planet Dulkis planning to drop a radioactive seed into the planet's core to refuel their spaceship, the Second Doctor, Jamie and Zoe must attempt to inspire the pacifist Dulcians to resist.

• BBC
• Patrick Troughton
• Frazer Hines
• Wendy Padbury
• Ronald Allen
• Kenneth Ives
• Arthur Cox
• Felicity Gibson
• Giles Block