Doctor Who: 10 Times The Earth Was Invaded
9. The Slow Invasion (The Power Of Three)
When the Earth suddenly became populated by identical, tiny black cubes, the Eleventh Doctor got to work. The problem was, the cubes didn't actually seem to be a threat. Considering them to be some kind of new viral sensation, taking them into their homes or discarding them on the street, the human race became accustomed to the strange cubes. Deciding to stay with Amy and Rory Pond to investigate the phenomenon, the Doctor soon became bored with the cubes' inactivity and departed on his travels.
However, the cubes began to activate - each with unusual or unexplainable powers. Working with the Brigadier's daughter Kate Stewart and her UNIT division, the Doctor observed cubes which could take a pulse, levitate, and count down. Now part of the furniture across the world, the cubes opened and began to trigger heart attacks in nearby humans. Unable to stop the activation, even the Doctor saw one of his hearts switched off by the unassuming boxes.
Uncovering that the cubes were part of the Shakri's plot to pest control the Earth, the Doctor located a teleport to their orbiting ship and destroyed their control panel. Reversing the cubes' functions, he used them to restart the hearts of the population, and himself, and foil the Shakri's scheme.
Absent in Doctor Who since the event, it's only a matter of time before the Shakri return to cleanse the Earth again.