The Doctor prepares to take Billy on her first proper trip in the TARDIS. She points out that the seats are too far from the central console, and wonders what the cost is. The Doctor admits that he stole it, just as there's a knock on the door. It's Nardole, who reminds the Doctor of his oath not to go off-world unless it's an emergency. The Doctor refuses to discuss it, and when Nardole asks why Billy is there, the Doctor tells him to be careful.
Once Nardole leaves, tells Billy to choose whether to go to the past or future. She chooses the future, and they depart.
At a colony in the future, Goodthing is outside in the field and says to her sister Kezzia that she's coming in. She tells the robot to wrap things up, while a series of microscopic robot drones gather overhead. Meanwhile, Kezzia tells Goodthing not to come in because they're having a bot problem, and tells her to keep smelling.
When Goodthing comes in, Kezzia puts on a fake smile and tells Goodthing that their mother is dead. The emoji badge on Goodthing's back turns into a frown, and Kezzia says that there are dozens of dead people. Goodthing insists that Kezzia can't say things like that, and Kezzia begs Goodthing to smile. A robot comes over and hugs Goodthing, and micro-bots fly down from the ceiling. Kezzia begs them to give Goodthing a moment, but the micro-bots envelop Goodthing and strip her to the bones in a second. As Kezzia breaks into tears, the bots advance on her.
The TARDiS materializes in the field outside of the colony, and the Doctor and Billy walk to the colony. He explains that it's one of Earths' first colonies, and Billy asks him about the oath Nardole mentioned. The Doctor tells her that something happened and as a result he made a promise to stay on Earth guarding a vault. He refuses to think about what happens if he doesn't get back, and spots the micro-bots flying overhead.
As they walk along, Billy's ear glows red briefly. The Doctor realizes that they've been fitted with communication devices using their nervous systems as hardware. There's no sign of anyone, and one of the man-sized bots comes out, a smiley emoji on its "face". The bot offers them blank badges: the Doctor's has a frowny face on it, the Billy's has a smiley face. They can only see the proper side of each other's badges, because the face is never on the side the owner is looking at. The Doctor figures that they're mood indicators, and they can't see what their own moods are. They put the badges on and they climb onto their backs, and they realize everyone can see what their moods are.
A bot serves them food and the Doctor wonders where the humans are. The Doctor looks around, frowning, and the emoji face on the bot briefly turns into a frown. He realizes that the whole place is waiting and they're too early. There are two servings for the Doctor, and he figures that the bots have detected his two hearts and consider him two people. While Billy takes that in, the Doctor figures that Earth sent the bots ahead to prepare the colony for the colonist
The Doctor and Billy continue looking around, and Billy wonders if they're going to leave before the colonists arrive. As he looks around, the Doctor finds a locket and picks it up, making sure that Billy doesn't see it. They find a greenhouse and Billy thanks the Doctor for bringing her. He asks her if he sounded convincing when he theorized that the colonists hadn't arrived, and Billy points out the badge on his back with a frowny face and says that he didn't. The Doctor insists that there should be a setup team there, and realizes that the sprinklers are spraying calcium-based fertilizer on the plants. He opens the bin, revealing skeletons inside being ground up.
A bot comes in showing a sad face, and the Doctor and Billy try to get past it. It reveals a skeletal emoji, and the Doctor and Billy run. More bots surround them, and the Doctor tells Billy to smile. She does, and her badge turns into a smiley face. The Doctor explains that the robots, the Vardy, malfunctioned and were supposed to make the colonists happy. He suggests that they give the Vardy what they want and smiles, and the emoji faces on the bots turn into smileys.
As they run for the TARDIS, Billy's smile slips and a skeletal-faced bot grabs her. The Doctor frees her with the sonic, but micro-bots fly after them. They get to the TARDIS and the Doctor tells Billy to stay there, and explains that he's going to go back and blow up the place. He figures that there is a colonist ship on the way, and he has to deal with it. Billy wonders why he has to deal with it, and suggests that he call the police. However, the Doctor runs back to the colony. Inside the TARDIS, Billy watches the Doctor on the monitor and then goes outside.
In the colony, the Doctor takes out Goodthing's locket and looks at the hologram of her relative. A bot appears and the Doctor insists that he's happy. The Vardy, convinced, finally walks past and the Doctor has an idea. He can hear someone breathing over the communication system, but they don't respond when he calls to them. Billy arrives and points out that the sign on the TARDIS says advice and assistant available upon request. The Doctor says that he's just passing by, but Billy doesn't believe him. He tells her to look at the wall, and explains that the micro-bots make up the walls of the colony.
The Doctor sets out to find a real wall, and points out that there must have been a real spaceship that the settlers arrived in... and it's somewhere inside the building. He finds a real wall with rust and rivets, and Billy spots a door. They go in and the Doctor closes the door behind them.
Throughout the colony, bots activate.
The Doctor points out that the spaceship life support is turning on and it knows that they're there. They find a map of the ship and the Doctor tells Billy to stay there and guide him using the map. Billy feeds him directions through the communication system and the Doctor tells her that they're going to blow up the ship. She wonders why he's allowed to blow up spaceships, and he insists that it's a moral imperative.
Billy spots the engine in the middle of the ship, just as the ship computer comes online.. The Doctor opens a hatch and an alarm goes off.
The bots' faces turn into skeletal emojis.
The Doctor works out that he can blow up the engine. Billy figures that she can go with the Doctor and takes a photo of the map, and then realizes that the Doctor already memorized it and left her there deliberately. She goes after him as he goes to the engine core. Billy finds an elderly corpse on a bier.
A Vardy enters the spaceship.
There's a book on the bier showing paintings and photographs through human history. Billy asks if people came there because something terrible happened on Earth, and wonders if they were the last hope. The Doctor explains that Earth was evacuated and there were a number of colony ships. The engine starts on its own and tells Billy that he could use help. As she leaves, she sees a boy, Praiseworthy. He asks if they're there yet.
As the Doctor shuts down the overloading engine, a Vardy advances on him. His back turned, the Doctor assumes that it's Billy until he sees its face reflected in the gauge. He knocks it off the catwalk but it grabs his leg and hangs on. The Doctor finally knocks it loose with a steam pipe, jams the wheel, and tells Billy to run. he finds her and Praiseworthy, and Praiseworthy asks where everywhere is.
Throughout the ship, the hibernation pods activate and the computer tells them to prepare for disembarkation. The Doctor tells Billy that they can't blow up the city and tells Billy that he got it wrong. He shuts down the overloading engine and explains that the surviving population of Earth is in the pods.
Praiseworthy leaves the ship.
Billy wonders what happens now, and the Doctor explains that the bots will kill the colonists when they go out. They greet the first colonist, Steadfast, and the Doctor tells him that no one is to leave the ship until he says that it's clear. He then leads Billy off, admitting that he doesn't have a plan. Billy shows him the bier and the Doctor works out that the best ones were woken to shepherd the Vardy. The book shows the dead woman, and the Doctor rearranges the photos to reflect the time of death. The woman died of natural causes, and then a few more people died, and then a lot more died just after. The Doctor suggests that the grief spread through the colony. The Vardy were meant to maintain happiness, and expanded the definition of happiness. They didn't know about grief, so they identified it as an enemy of happiness and killed everyone who wasn't happy. The Doctor gives Billy Goodthing's locket, which shows Praiseworthy, and explains that he found it in the greenhouse. When the awakening colonists find out what happened, there'll be a massacre.
Praiseworthy walks through the empty colony as a Vardy watches.
When the other colonists wake up, the Doctor tells them that the Vardy are having ideas of their own.
A Vardy confronts Praiseworthy and offers him a badge.
The colonists grab weapons and the Doctor insists that the Vardy aren't their enemy. Billy realizes that Praiseworthy is gone.
Praiseworthy asks where his mother is, and the Vardy looks unhappy.
The colonists and Billy find the Vardy and Praiseworthy. As Praiseworthy wonders what's going on, the Vardy grab his hands. Billy runs over and tries to reassure him, but it doesn't work and the colonists kill one Vardy. Billy warns that it's not just one robot, and the micro-bots making up the walls attack. The Doctor realizes that the Vardy are alive, removes the "dead" Vardy's head, and sonics the circuitry. There's a burst of light.
Later, the Doctor explains the story of the Magic Haddock. It didn't think like humans did, and it didn't grant wishes the way its owner wanted it to. The Doctor tells the colonists that he wiped the Vardy's programming,
Written by Gadfly on Apr 23, 2017