Revolving Doors ( comic story ) Summary . When the Doctor and Gabby arrive in London , they are lured into a trap by an exiled alien who intends to use the Doctor ' s pain to open the door to its freedom . Plot . The Tenth Doctor has briefly left Cindy Wu at Sunset Park to allow her to rest . The Doctor and Gabby are travelling in the TARDIS when they hit dimensional turbulence which activates the randomiser . After the TARDIS lands , the Doctor and Gabby exit , expecting a surprise , when he realises they are only in London . While Gabby is excited , the Doctor is less pleased , saying they need to leave . Gabby protests , and the Doctor gets angry , but is interrupted by a scream in the distance . Running to find the source of the noise , they arrive by the door of a stockroom , where a woman is talking to security guards , explaining that she saw a " monster " inside . The Doctor reluctantly agrees to stay for a short while , walking towards the stockroom . Elsewhere , a man watches them , talking to an unknown voice . Walking through the stockroom , the Doctor asks Gabby if she knows when a stockroom isn ' t a stockroom . She doesn ' t believe he ' s being serious , so he reveals a doorway to another dimension , which shows a creature . He is being watched by a group of similar creatures . The creatures say that the Doctor will need their help against " the exiled " . The Doctor tells Gabby that the creature isn ' t actually there , and the doorway is just a 4 - D echo . The Doctor tries to lock onto the source of the dimensional bleed , and isn ' t able to find out what it was , but knows where to look . The two of them arrive at The Key , a think - tank established by Aaron Crossland , which had been abandoned for six months . He unlocks the door , and they walk inside , as Gabby asks him why being in London is such a problem for him . He says that bad stuff always happens to him in London . They are interrupted by Crossland himself , who welcomes them to The Key . As he speaks , he begins to glow , and a door behind him opens to reveal a creature similar to the one they saw earlier in the echo , but larger and redder . The Doctor uses his sonic screwdriver , and detects the creature is giving off massive psionic power readings . He asks it what it is , and it calls itself the Reach . He asks it what it wants , and it says it wants to reach its home again . The Doctor asks it how , and Crossland says it will break his heart . He attacks Gabby , lifting her up in a glowing disc . The Doctor tells him to put Gabby down , but Crossland throws her out a door into the other dimension . The door slams as the Doctor tries to get through it . He asks Crossland where she is , and Crossland tells him she is in " the space between spaces " , and that the Doctor must follow her in to be able to save her . The Doctor knows it ' s a trap , but opens the door with his sonic screwdriver regardless , and leaps in to follow her . He lands on the ground , and looks around him . He sees who he think is Gabby lying nearby , and turns her over to find it ' s Martha Jones , who has been knocked out by a stun mine . A robotic figure walks up behind him , and attempts to incinerate him with blasts of fire from its hands , but the Doctor uses his screwdriver to push the fire back at it , killing it . As another " door " opens , the Doctor apologizes to Martha and leaves in it . He exits the door in a house , hearing voices . Looking at photographs , he realises he is in the house of Donna Noble . Knowing he can ' t stay , he leaves through another door , and arrives at the Powell Estate , before it has finished being developed . As he collapses to his knees , Crossland and the Reach watch him , saying that the scenarios have activated the correct emotional response . The Doctor hears a voice behind him , and Gabby walks through a door . As the Doctor runs through , he asks her how she survived . She says some " familiar faces " caught her as she fell . As Crossland and the Reach prepare to finish their plan , the Doctor and Gabby arrive through a door , revealing that the rest of the Reach ' s species helped them . The Doctor explains that he knows the Reach ' s plan , and asks the Reach whether it has anything to say . It grabs them with its tentacles and pulls them towards the door . As they get pulled closer , the Doctor tries to speak to Crossland , saying that the Reach ' s plan will not only destroy his species , but backfire and destroy half of London . Crossland slowly loses connection to the Reach as it protests . Crossland , now in control , apologizes and throws himself at the Reach . It lets go of the Doctor and Gabby as the door slams . As the two of them run away , exiting the building , the room behind them explodes , destroying the building but also sealing the dimensional link . The Doctor and Gabby return to the TARDIS , and Gabby asks him what he would have done if he had lost her . Avoiding the question , he asks her where she wants to go next . They enter the TARDIS and it dematerialises . Notes . " to be added " External links . " to be added "