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?