Doctor Who: Into the Nowhere (Time Trips)

The Eleventh Doctor and Clara land on an unknown alien planet. To the Doctor s delight and Clara s astonishment, it really is unknown. It s a planet the Doctor has never seen. It s not on any maps, it s not referenced on any star charts or in the TARDIS data banks. It doesn t even have a name. What could be so terrible that its existence has been erased?