We pick up from the end of the Christmas special, with Ruby walking into the TARDIS. She wants to know the Doctor's real name but he doesn't know it because he was adopted by the posh TIme Lords who gave everyone these types of titles (we get a Rani mention!)

Ruby asks him about the TARDIS, the police box outside, and where Gallifrey is. The Doctor is far less tinged with sadness as usual as he states his home planet was destroyed in a genocide. He is glad to be alive.

The Doctor takes Ruby on a trip to demonstrate that this is really a time machine. They go to the distant past. Ruby asks what happens if she steps on.a butterfly. The Doctor doubts that will happen, but of course it's exactly what does and Ruby turns into a human butterfly who speaks crisply and threatens to kill the Doctor if he says she did something wrong. The Doctor picks up the butterfly from under her heel and sets it free, and RUby turns back into a human.

The Doctor decides that's enough of this locale and they return to the TARDIS, where he allows Ruby to choose the next destination. She shouts out random numbers.

They land in a futuristic space station, where things seem broken and they meet a dinosaur like thing and run away to a more well lit room. The Doctor realizes it's a baby farm -- no, not for growing babies for food, but to replenish the population. This is the far future where humans speak one language and the TARDIS translates. Ruby realizes her adoptive mother is long dead. The Doctor sets up her phone so she can call Carla and tells her to do so.

Ruby is amazed that on Earth it's right after she left. The Doctor is more interested in what's wrong with this place. Suddnely a baby in an electronic stroller comes rollin gin. He can talk and he thinks Ruby and the Doctor are his parents. He says he's telling the others that Mummy and Daddy are here.

The Doctor and Ruby follow him to a room full of babies. They say they worked hard while they were gone and want them to be proud. They've kept oxygen going and the farm running and one baby pulls strings without knowing what they do. One baby is Captain Poppy who is in charge. The Doctor tells her he's sorry but they're not their parents. Ruby says but we are your friends, Ruby and the Doctor, and we're going to help you. The babies wonder why their parents abandoned them.

The Doctor investigates and d iscovers the adults all abandoned this space station and the babies grew up but stayed babies. Poppy wonders if they did something wrong since they aren't supposed to look like this. The Doctor says no one is wrong for being who they are. He was lost too but he is himself and he is lovely. He says his superpower is that there is no one in the universe exactly like him and that's theirs too.

Ruby asks how they manage. There's a Nanny (Nan-E), which is a robot who comes to lfe and makes the children blow their noses.

Ruby asks about the "dog" downstairs and the babies freak out saying it's the bogeyman. Ruby tels Nan-E to tell them there's no such thing. Nan-E is scared of the bogeyman too.

The Doctor puts on a headset and realizes there's a buildup of pressure by the Bogeyman downstairs. How do they fix it? Nan-E insists he go to a storage portal on this floor. Ruby runs after him and asks if he helps others, if that's his purpose. He says no. Ruby hopes it will not take years since Carla is waiting for her. The Doctor realizes Ruby is connected to what's going on here because she was abandoned as a baby too.

The Doctor and Ruby head toward the storage unit. There is a flash of memory and then it is snowing, as if the snow from Ruby's abandonment came into the space station. A woman calls to them to get in here already. She is the woman voicing Nan-E and her name is Jocelyn. She is the only one left. She shows them a video of crew members saying they are leaving under protest and explains the government closed the space station but forbid turning off the birthing machine so she has been taking care of the babies. However, there are limited food and air supplies, and the station can't move so they can't get to a refugee center. The Doctor realizes the TARDIS can help but only if they get past the Bogeyman. Ruby realizes this is like a children's story. Suddenly, they see Eric in the basement, bravely rolling his pram toward the Bogeyman. He won't listen when Jocelyn as Nan-E tells him to turn around and go back upstairs. Ruby said there is no such thing as the Bogeyman and he believes her. Ruby realizes this is her fault and she and the Doctor hurry to save Eric.

Eric's pram is empty and the Bogeyman is nowhere to be seen. The Doctor realizes Eric is hiding. They find the baby in a closet but the Bogeyman approaches and corners them. Suddenly, the other babies appear and use a flamethrower to scare off the Bogeyman. The Doctor says they have been brilliant but can't be down here. Jocelyn tells them as Nan-E to get upstairs or no dinner. The babies leave and the Doctor says he has to figure out what's going on. Ruby refuses to leave his side.

Jocelyn says this started as rattling in the pipes six years ago. Ruby realizes that's when the babies were born.

The Doctor and Ruby find a dropping made by the monster and want to analyze it. Ruby slips on the wet sewage and the stuff drips on her. She is not amused.

The Doctor finds a machine and realizes that the space station made the Bogeyman because it thought that children need stories so it made a scary monster for them. It also was literal and made the monster out of snot.

The Bogeyman approaches but Jocelyn can now control things and she decides to lure it to an airlock and throw it out into space.

This lets what little oxygen is remaining out little by little. The Doctor tells Ruby to stop Jocelyn. Take the sonic screwdriver out of her control panel. He will rescue the Bogeyman.

The babies are crying and saying Nan-E stop, you'll hurt the monster.

Ruby gets there just in time, with 1% oxygen remaining and stops Jocelyn, telling her you save them ALL. Jocelyn cries.

In the baby room, the space babies say Nan-E was very naughty. But they love her anyway.

The Doctor shows them the world they will be going to. He says the reason there was so much pressure in the space station was that the computer didn't know what to do and tored dirty nappies (diapers) in the basement. JEttisoning all that sewage gives the space station enough thrust to move to the refugee world.

The Doctor and Ruby get ready to go. The Doctor wants Ruby to travel with him but only on one condition. They can never, ever go to the church on the day she was born because it would create a terrible paradox that would stop them from ever meeting. RUby says we ARE going to see my Mum on Christmas.

At home, Carla is on the phone complaining about Ruby disappearing. THe TARDIS suddenly lands in her kitchen.

Ruby comes out and tells the Doctor to come with her. He says he's coming in a minute. He practices again saying that on his world they use titles like Bishop etc.

He freezes as he looks at a scan on the wall of Ruby's DNA...