This is a special episode of the British Science-Fiction television
series
Doctor Who,
marking the programme's 50th anniversary.
In the midst of the Time War between the Time Lords and the Daleks, the War Doctor - an incarnation of the Doctor about 400 years younger than the Eleventh Doctor — decides to trigger an ancient and sentient weapon called the Moment to destroy both sides. The Moment's humanoid interface, resembling Rose Tyler, shows what the War Doctor's future would be after the Time Lords are destroyed but the Doctor survives. The Moment opens a fissure linking the War Doctor to the Tenth and Eleventh Doctors in 1562 England. In 1562, the Zygons enter three-dimensional paintings made with the Time Lords' stasis cubes, and go into suspended animation to emerge in the present. After breaking out of the paintings in the National Gallery in the present, the Zygons take the forms of members of the military organisation UNIT so that they can utilise weapons and technology kept by UNIT in the Tower of London.