Alternate timeline (Klein's Story)

In an alternate timeline inhabited by Elizabeth Klein, which was created as a result of a mistake made by the Seventh Doctor and Ace at Colditz Castle, 1944, when Ace's walkman was left behind, found by the Nazis and the technology inside was reverse engineered to create lasers which won them World War II. (AUDIO: ''Klein's Story)

Klein's original timeline
During this timeline, Klein had been studying the principles of time travel when she was sought out by Major Jonas Faber, who requested her assistance in researching alien technology secretly in possession of the Reich, and the two eventually began a romantic relationship. The Seventh Doctor eventually returned the Colditz castle, where he was gunned down and his TARDIS was taken away and stored. After much insistence, Klein was allowed access to the TARDIS to study it, but, without the key, she couldn't effect entry. She was contacted by a man called Johann Schmidt, who was secretly an alternate version of the Eighth Doctor, who said he would give her the key and requested the opportunity to work alongside her.

After cooperating with Schmidt, Klein wished to use the TARDIS to travel back to when the Seventh Doctor was still alive and force him to reveal the TARDIS' flight controls to her, but Faber immediately dismissed the idea. When Schmidt tried to convince her to do it anyway, Faber shot him, and Klein left in the TARDIS to secure a new future for the Reich. However, in doing so, she gave the Doctor the opportunity to avert this future by preventing the Nazi's from finding the laser technology, negating this timeline and making Klein an anomaly. (AUDIO: Colditz, Klein's Story)