Klein ' s Story ( audio story ) Publisher ' s summary . Elizabeth Klein is an anomaly , a renegade from an alternate future in which the Nazi s won World War II . To get to know his latest companion , the Doctor invites Klein to tell him how exactly she came to be in possession of his TARDIS and of the events that led to her trip into the past to Colditz Castle . Plot . The Doctor and Klein finally find the TARDIS after having seen the British army arrive to help Sylvia O ' Donnell and her husband . The Doctor ponders about what to do with Klein , while she rebuffs him with the fact that taking her with him was his idea . The Doctor makes it clear that he ' ll constantly have his eye on Klein so as to ensure that she doesn ' t attempt to use his TARDIS to recreate her original timeline . The pair enter the ship where Klein expresses surprise about the change to the TARDIS interior . The Doctor programs a destination for the TARDIS , but Klein is still not contemned with the idea of being a forced travelling companion , nor is she happy with the Doctor ' s notion that she is merely an anomaly in time . She dictates that the she and the Doctor know nothing about each other and henceforth have no reason to trust nor like each other . The Doctor agrees and decides that they have to find some even ground on which to cooperate . He suggests that , in an attempt to get to know Klein , she could tell him about her original timeline ; the timeline that she lived in before she took his TARDIS back to Colditz Castle in 1944 . Klein concurs with this idea and the Doctor asks her to tell him the details about what made her take her first voyage in the TARDIS . Klein tells him that in 1962 , she was researching physics at Cambridge when she was called upon a airship bound for Berlin , where her arrival was awaited by Jonas Faber , a Nazi Major . On her arrival on the airship , Faber greeted her warmly and told her that he travelled all the way from Germany to recruit Klein for a special project that he is overseeing , the he feels her characteristics and work establishment would be vital for . Faber informs her that , to Klein ' s scepticism , that the Nazi ' s had been privy to the knowledge of extraterrestrial incursions previously and that Klein had previously speculated on the possibility . Klein enquires as to what her role in the project is . Faber tells her that she will be working with recovered alien technology to investigate and research their properties for the benefit for the Third Reich . He claims that the reason for the research only just started being conducted was due to Hitler having the technology taken and hidden away with their existence denied , a policy which was lifted after his recent suicide . Klein eventually accepts to role . The Doctor finishes making the tea and Klein tells him about the types of technology she was given access to for the benefit of her research , over a variety of species . The Doctor speaks very nonchalantly about the existence of other races , but Klein again rebuffs him based on her feelings about life - long beliefs being proven . Klein tells the Doctor that despite all the technology she was given access to , she wasn ' t allowed access to the TARDIS until a lot later , after she had become romantically involved with Faber . During a dinner date with Faber , Klein tells him about the progress of her work , when she broaches the possibility of her work resulting in the invention of time travel . Upon hearing this , Faber becomes intrigued . When Klein claims surprise that none of the species she is utilising the technology of have been capable of time travel , Faber relates to her a incursion at Colditz Castle back during the war . He tells her that back in 1944 , two time travellers , and man and a girl known as ' The Doctor ' and ' Ace ' , arrived at Colditz from the future , when the girl was executed but the man escaped into his time machine . He reveals that what came to be known as Laser technology was found in a small device left behind by the Doctor , much to Klein ' s delight . He then reveals that the Reich have the time machine in a security bunker ; the Doctor returned 10 years later at a border checkpoint where he was gunned down and killed by border patrol who mistook his umbrella for a rifle . Klein asks why she hasn ' t been given access to the time machine , when Faber queries whether she ' s considered the implications of examining it ' s technology , such as changing history . The Doctor lectures Klein about the responsibility that comes with the ability to change history , which Klein turns on him as a hypocritical statement . He insists that he isn ' t sure why he returned to 1955 as that event never ended up happening to him . When the Doctor inquires how she convinced Faber allow her to investigate to the TARDIS , she tells him that after Hitler ' s death and a period of political unrest , she was eventually given access to it and permitted to study it . " To be continued . . . "