The Doctor

The Doctor takes his new travelling companion Ruby Sunday to Earth 155 million years into the past to a region that would eventually become the American town of Green River, Wyoming. There Ruby accidentally steps on a monarch butterfly so altering her timeline. The Doctor witnesses this when Ruby transforms into a reptilian humanoid version of herself named Rubithon Blue of the 57th Hemisphere Hatchlings. The Doctor though is able to revive the butterfly and so Ruby reverts back to her human form, completely unaware of her transformation.

Before anything else happens The Doctor ushers Ruby back into the TARDIS, and after Ruby chooses a year in the future they travel to the year 21506. On exiting the TARDIS they find themselves aboard a space station orbiting a planet. Wandering down a utility corridor, The Doctor discovers the space station’s poor electrical infrastructure, but before he can fix it, they encounter a monstrous, slimy bipedal creature.

To escape the creature, which chases after them, they find an elevator which takes them up to a higher level to a room where they discover babies encased in pods. The Doctor deduces that this is a baby farm. He also discovers they are stationed above the planet Pacifica Del Rio.

Ruby Sunday

Before they discover anymore, they are interrupted by a baby called Eric that arrives in a motorised pram. Eric though mistakes The Doctor and Ruby for his Mummy and Daddy. On learning that Eric can not only talk but is also a crewmember of the space station, Eric takes The Doctor and Ruby to meet the rest of the crew, who are also all intelligent babies. They are led by Captain Poppy, who runs the space station in anticipation of the return of their parents, revealing that they took over the station from the adults. The Doctor discovers that the original adult crew abandoned the space station but who left the birth machines running, allowing the babies’ intelligences to develop but stunting their physical growths.

The babies are under the care of a Nanoelectric Maxiform, called Nan-E. The babies panic when The Doctor mentions the creature below, they call it The Bogeyman. The Doctor communicates with Nan-E about a high-pressure buildup in Hull-3-B that could destroy the space station, and she directs him to storage unit 3-5-7.

Exiting the TARDIS

On the way there, The Doctor mulls over the connections of childhood abandonment between Ruby and the babies, Ruby being left behind with nothing to indicate the whereabouts of her parents. He flashes back to that snowy night on Ruby Road, where he remembers a mysterious hooded figure. The flashback physically brings back snowflakes into the space station, The Doctor remarks that he has never experienced anything like this before. At storage unit 3-5-7, Nan-E is revealed to be an actual person, former on-site accountant Jocelyn Sancerre. She reveals that the crew returned home under protest due to a recession that closed the baby station but laws do not permit closure of the birth machine. She has spent six years caring for the babies, but laments that limited resources will eventually be their demise. The Doctor discovers that the fifth planet in their solar system, Mondo Caroon, can accept refugees. The Doctor proposes the TARDIS can provide transportation to Mondo Caroon, but to reach the TARDIS they first must get past The Bogeyman.

On returning to the babies The Doctor and Ruby discover that Eric has summoned the courage to face The Bogeyman alone. The Doctor and Ruby rush down to the lower levels to save him, but only discover his empty pram. They attempt to lure The Bogeyman to try and save Eric, but then, to their relief, they discover Eric hidden away in a nearby compartment. The creature then arrives and gives chase while Ruby attempts to comfort a crying Eric. The creature corners them in a dead end, but they are saved by Poppy, who wards The Bogeyman off with a flamethrower. Jocelyn directs the babies back to safety, while The Doctor and Ruby investigate the creature that Jocelyn first encountered six years ago, when the babies were first born. The Doctor finds the creature has left behind some ‘spoor’ and takes it to a nearby machine to analyse its contents.

The Doctor finds The Bogeyman's appearance mysterious as he has the urge to run away from it. After finding the space station’s programming he discovers that the space station’s parthenogenesis machine intentionally grew The Bogeyman as part of its misguided attempt to entertain the children. It also literally created the creature out of the babies’ bogies.

Rubithon Blue

The creature finds them and Jocelyn has The Doctor and Ruby lead The Bogeyman to an airlock so she can eject it into space, but Ruby points out that the creature appeared the same time the babies were born, thus is actually one of them. On learning that The Bogeyman is one of the children, The Doctor sends Ruby to stop Jocelyn and lets himself into the airlock to save the creature. He pushes a button that reverses the vacuum and closes the airlock so saving the creature.

The Doctor realises that by reworking the space station he can get it to move to Mondo Caroon. He does this by utilising Hull-3-B’s pressure buildup where six years of methane gas from the babies’ diapers has built up a lot of potential fuel that can be used to propel the space station towards the refugee planet.

Returning to the TARDIS, The Doctor gives Ruby her own TARDIS key, but warns her that he can never take her back to the day when as a baby she was abandoned outside the church on Ruby Road, lest it creates a paradox. On returning to Ruby’s home, The Doctor performs a DNA scan on an unsuspecting Ruby, and it begins to snow inside the TARDIS.