Currently in his Eighth Incarnation, the Doctor is an alien from a distant world. More specifically, the Doctor is a Time Lord, a wise race of beings from the planet Gallifrey. Time Lords are immensely intelligent and able to regenerate into new bodies after being subjected to injuries or conditions that would otherwise lead to death. This ability to regenerate allows the Time Lords to live for centuries, if not millennia. The Doctor has regenerated seven times already, placing him in his eighth life. The Doctor travels through space and time in a blue box known as the TARDIS; Time and Relative Dimension in Space. The box is bigger on the inside and capable of going just about anywhere.
Ever since the start of the Time War, a mighty war fought between the Time Lords and a warlike race known as the Daleks, the Doctor has been running around the universe, trying to negate its effects. He has saved entire planets at the cost of countless other races. As the Time War burns across space and time, the prospect of the universe looks grim. To prevent the deaths of his closest companions, the Doctor travels alone, haunted by the deaths of other companions such as C'rizz, Tamsin, and Lucie as well as the death of his great grandson, Alex Campbell.
Now, accompanied only by his TARDIS and his sonic screwdriver, the Doctor is responding to a Time Lord signal beckoning him through the TARDIS. The Doctor has seen many adventures and done many impossible things. Nothing, however, could have prepared him for the Cruciform. Tricked by a rogue Time Lord, the Doctor is trapped in the digital copy of the universe. He must enlist the help of the denizens of this universe to break free before more Time Lords are drawn into the Cruciform, unable to stop the wave of destruction unleashed by the mighty Dalek Empire.