It's the last day of the Time War and everything seems to be lost. The War Doctor steals a deadly weapon and tries to destroy Gallifrey but the weapon has a conciousness and shows him his future. This brings him together with his Tenth and Eleventh incarnation who are trying to save Earth from the Zygons. During the time of Elizabeth the First, the Zygons enter paintings that are like stasis cubes and so they have time to wait until Earth is more advanced. Elizabeth helps the Doctors to get back into the present and there they are confronted with two versions of Kate Stewart. The real one would destroy Earth to save all the other people from the Zygons but the Doctors wipe their memory so nobody knows who's a Zygon and who isn't. The War Doctor has seen enough and is willing to destroy Gallifrey for the future he has seen but this time he is joined by two of his other incarnations. Will they do it again or will the Doctors change their own past?
What came into my mind when I first watched this episode was "wow". It was just totally brilliant and I loved it. I still love it after watching it a second and a third time. You still pick up so many details that you haven't seen on the first go. I don't want to say too much because there are probably still some people out there who haven't seen the episode yet. The little nods to the past of Doctor Who were lovely and I liked Billie Pipers role a lot even if she didn't come back as expected. There were so many funny moments between the Doctors and I loved the scenes with the fez. It made me smile. The ending was just totally amazing and I wouldn't have expected that. This was truly a celebration of 50 years of Doctor Who and I'm looking forward to the next 50 years.