The War Doctor retreats to the TARDIS after the final battle in the Time War.
As he ponders his next action, a visitor materializes in the TARDIS. He introduces himself as Richard. The Doctor is stunned. He asks how Richard got inside the TARDIS.
Richard reveals his own personal Time Travel device. As the Doctor ponders about the technology needed to invade the TARDIS, Richard comments that he can sense he and The Doctor are similar. He hypothesizes that The Doctor may be another version of himself. He then says he always wondered that if he killed an alternate version of himself, would he die as well?
Richard draws a triple barreled pistol from his pocket and before The Doctor can react he is shot several times. The Doctor falls to the floor writhing in pain. Richard winces and says. “Oh, the pain is unbearable. This is my end as well as yours. So many experiments I never got to complete. Oh, the pain… wait a minute. Its only emotional pain. Hmmm… I thought I got rid of my empathy.”
As The Doctor lay on the floor dying, Richard fiddles with the TARDIS controls and concludes it is a time machine. He then ponders what would happen if a person time traveled inside a time machine while it was traveling thru time itself. He activates the TARDIS (using several manual overrides to overcome its security systems and personality) to travel backward in time as he uses his own device to travel forward in time.
After an intense flash of light, Richard dematerializes from the TARDIS and several new (and unconscious) passengers appear aboard it. The Doctor, however, has just regenerated…