Turn Left ( TV story ) Turn Left was the eleventh episode of the fourth series of " Doctor Who " . It was the first Doctor - lite episode to focus on the main companion without the Doctor , and marked the first major reappearance of Rose Tyler . It also showed a parallel world showing what would have happened had Donna not met with the Tenth Doctor in " The Runaway Bride " . In that world , without Donna to convince him to leave during his encounter with the Empress of the Racnoss , the Doctor ended up drowning in the resulting flood under the Thames , because of this , many of the Doctor ' s companions and friends would have died , and without the Doctor around to stop an overwhelming threat on the horizon , all things would eventually be destroyed . Much of series 3 and 4 ' s events set on present day Earth would still occur , but would have cost more lives without the Doctor ' s intervention . The Master would not have been present in his Harold Saxon persona as the Doctor would not have been alive to go to the year 100 trillion to allow him to escape the end of the universe . Indeed , the year 100 trillion itself would never occur , as the " stars go out " in 2009 . The main villains in this episode were agents of the Trickster ' s Brigade , a group who fed off altering timelines . They are also the only enemy to have been fought in " Doctor Who " and its spin off shows " Torchwood " and " The Sarah Jane Adventures " . Synopsis . On an alien planet , Donna meets a fortune teller , who launches her into a world based on one question : " What would happen if Donna never met the Tenth Doctor ? " Without the Doctor , the whole world is in ruin , and a mysterious blonde tries to warn Donna of the oncoming darkness . . . Now a simple refugee , Donna is the only one who can undo the damage . But how ? Plot . The Tenth Doctor and Donna are in a bustling market place on an alien world , mixing with the locals . Donna wanders away from the Doctor to explore as he chats away with a merchant . A mysterious fortune teller asks if she wants her future told , but Donna declines . The fortune teller then says the reading is free for those with red hair . Donna smiles and relents . As the fortune teller asks about Donna ' s past , she sees there is a man in her life that changed everything . Donna tells the fortuneteller that she met the man on Christmas Eve , when she ended up on his spaceship on her wedding day . She was a temp at H . C . Clements on Earth . Donna experiences a flashback , but the fortune teller dismisses it . The teller asks Donna what event led to her meeting with the Doctor and Donna says it was six months before . At that time , Donna and her mother were in a car at a T - junction , arguing about her future . Sylvia tried to persuade Donna to turn right and ask businessman Jival Chowdry for a job ; but Donna turned left to go to her planned temp job at H . C . Clements . After experiencing another flashback , Donna is now panicking , but the fortune teller asks her what would have happened if she turned right as something crawls onto Donna ' s back . Scared , Donna falls under the fortune teller ' s influence and , in the past , she gives in to her mother ' s nagging and turns right , altering the course of her life as well as the future of all existence . On Christmas Eve , Donna is at a Christmas party with the rest of the staff from her workplace . She has just been promoted to Jival Chowdry ' s personal assistant . Suddenly the Racnoss Webstar attacks London , and is destroyed by the army at a terrible cost . During the chaos , Alice stares at Donna ' s back , looking terrified . When Donna acts astonished that Alice ' s attention is focused on her despite the ongoing chaos , Alice , terrified , says that there is something on Donna ' s back . After this , Donna runs to the Webstar ' s general location . There she finds an ambulance . Near the ambulance and a group of UNIT vehicles , Donna overhears a UNIT officer talking into a radio about " the Doctor " who drowned beneath the Thames . As the Doctor ' s body is loaded into an ambulance , a hand falls out of the stretcher , dropping a sonic screwdriver . As Donna walks away , Rose Tyler comes running down the street and asks for information about the body that has just been loaded into the ambulance . She is stunned to hear that it was the Doctor , despite Donna ' s assurances that it could have been any doctor . Rose vanishes moments later . Donna has been fired from her job . Chowdry tries to tell her that he has to lay people off because half of his contracts are on the other side of the river . Even though it has been several months since the Racnoss attack , the Thames is still closed off . Meanwhile , the Royal Hope Hospital is mysteriously transported to the Moon . When it returns , there is only one survivor : medical student Oliver Morgenstern , who relates the terrible events involving " talking rhinos " . Wilfred , Donna ' s grandfather , believes that the rhinos are aliens . Morgenstern tells reporters he only survived when fellow medical student Martha Jones gave him the last of her oxygen , and that Sarah Jane Smith had taken control of the situation and said she could stop the MRI . Sarah Jane ' s body was reported as being recovered from the hospital , while it is feared that Sarah Jane ' s son Luke and Luke ' s teenage friends Maria Jackson and Clyde Langer had also perished inside . As Donna digests the terrible news , Rose tells Donna that she should go to the country for Christmas . When Donna says that she can ' t afford it , Rose mentions the raffle ticket she bought at work ; First prize , luxury weekend break . Donna looks confused and leaves . Donna takes the woman ' s advice , and treats her mum and grandfather to a Christmas holiday in the English countryside . On Christmas morning , they watch the telly in disbelief as a replica of the " Titanic " falls on Buckingham Palace . The three run outside and watch , horrified , as a mushroom cloud rises above London . As the housemaid comes in to bring the Nobles their breakfast , she then turns to Donna and repeatedly shouts " you ' ve got something on your back " in Spanish . Now refugees since all of southern England has been flooded with radiation , the Nobles are forced to move to Leeds . France has closed its borders . They are allocated a house that is shared with two other families . In 2009 , the United States pledges to help Britain with monetary relief but must abandon the plan when their own crisis strikes : sixty million American s are turned into Adipose . Some time later , Donna finds soldiers firing at cars when the Sontaran s activate the ATMOS devices , covering the Earth with a poisonous fog . A soldier notices something on Donna ' s back and holds her at gunpoint , but she is released when nothing is there . That night , Donna meets Rose for a third time . Rose explains that the Torchwood team , aboard the Sontaran ship , are trying to stop the catastrophe . Suddenly , the sky is cleared by an atmospheric converter . Gwen Cooper and Ianto Jones have given their lives to achieve this , and Captain Jack Harkness has been transported to the Sontaran homeworld . Rose refuses to tell Donna her name . She only says that she has " crossed reality " , and tries to explain that Donna had saved the Doctor ' s life in an alternate timeline , though Donna insists that she had never met him . Rose warns Donna the coming " darkness " threatens every single universe . Donna tries to walk away , but Rose tells her that she will have to go with her when she is ready and that she has three weeks to decide . She warns Donna that when she comes with her , Donna will die . Then she disappears . Three weeks later , the genial Italian family in Donna ' s house is evicted as England is now " only for the English " . Since the oceans are closed off , they must be taken to a " labour camp " . " That ' s what they called them , " Wilfred says horrified , " it ' s happening again ! " Later at night , Donna and Wilf talk about recent events while looking through his telescope . He notices that the constellation of Orion has gone , though there are no clouds . As the stars disappear from the sky , Donna finds Rose , and tells her that she is ready . Rose takes Donna to a UNIT base and shows her the TARDIS — salvaged from beneath the River Thames — which is dying after the Doctor ' s death . Rose asks Donna if she wants to see the creature on her back . They step into a circle of mirrors and lights , with pieces of technology which seem to be scavenged from the TARDIS . Rose switches on a light which reveals what is on Donna ' s back : a " Time Beetle " . Donna is horrified and begs Rose to get it off her . However , Rose explains that it " feeds off time by changing time " and that she thinks the beetle is in a state of flux , although when Donna asks what that means , Rose says she doesn ' t know , but that it ' s something the Doctor would say . She also says the beetle cannot be removed ; when Donna becomes angry that Rose said she was special but Donna thinks it wasn ' t her , but the beetle , Rose says that actually they ' re getting separate readings from Donna that make it seem like reality is bending around her . Donna asks , " What can I do to get rid of it ? " to which Rose replies , " You ' re gonna travel in time . " They prepare Donna , and take her back to the circle of mirrors and technology , with cables running into the TARDIS . At first Donna thinks she is going to see the creature again and protests , but Rose informs her the mirrors are " incidental " , and that they " bounce Chronon energy at the centre , which we control and decide the destination . " Donna realises that this is the time machine they will be using . hen Donna asks , " How d ' you know it ' s gonna work ? " Rose replies " Hmm ? Oh , yeah we don ' t . . . We ' re just guessing " . Donna says " I ' m ready , ' cuz I understand now , you said I was gonna die but , you mean , this whole world is gonna blink out of existence , but that ' s not dying , ' cuz a better world takes its place — the Doctor ' s world . And I ' m still alive . " Rose remains silent . " That ' s right , isn ' t it ? " Donna tries to get confirmation of her belief , but Rose only replies sadly , " I ' m sorry . " Before Donna can learn what will happen , the Lodestone is activated , and she is sent back in time . Donna lands six months before meeting the Doctor on Monday the 25th , elated that the time travel worked , but quickly realises that she is on Sutton Court , a half a mile away from her past self , and has only got four minutes to prevent her past self from turning right on Little Sutton Street . She tries to run to herself , but knows that she will not make it in time . Donna understands what the woman meant about her death , and she sees a haulage truck coming along that has just passed by her past self . She steps in front of the truck , which screeches to a stop . Before Donna dies , Rose appears and whispers something into her ear to tell the Doctor . At the intersection , Donna ' s past self decides that instead of sitting in backed up traffic , she will turn left . As the original timeline reasserts itself , Donna regains consciousness in the fortune teller ' s stall on Shan Shen , as the Time Beetle on her back releases itself and dies . The baffled and terrified fortune teller flees , screaming , " You were so strong . What are you ! ? What will you be ? ! " The Doctor , who has been blissfully unaware of all that ' s happened , enters and an emotionally spent Donna collapses into his arms . When he asks why , she simply replies , " I don ' t know ! " and proceeds to hug him again . Upon examining the beetle , the Doctor tells Donna that it is part of the Trickster ' s Brigade and that normally it affects one person and the universe compensates , but in Donna ' s case , it created a parallel universe . The Doctor muses on all of the coincidences surrounding Donna : the fact that she had two parallel worlds that formed around her ( this one and the one in the Library ) and that he ' s met her and her grandfather twice . " In the whole wide universe , I met you again , " he notes . The Doctor concludes that they seem to be somehow linked . Donna tells the Doctor she is nothing special , but he counters saying that she ' s " brilliant " . Hearing that triggers Donna ' s memories of the parallel world and she mentions Rose to the Doctor and her warning about the coming darkness . When Donna mentions Rose said something about parallel worlds and was blonde , the Doctor starts to realise who Donna saw . When asked if she remembered Rose ' s name , Donna said she was never told it , but she does remember the two words Rose whispered into her ear : " Bad Wolf " . Terrified and now sure of who Donna met , the Doctor runs out into the market square to see the words " Bad Wolf " everywhere : on posters pasted onto the walls , on the ceremonial flags hanging over the market , even on the TARDIS itself . Inside the TARDIS , the control room is glowing red and the Cloister Bell is ringing . When Donna asks what ' s going on , the Doctor replies , looking horror stricken , " It ' s the end of the universe . " Story notes . Filming locations . " to be added "