Just before "Planet Of Fire", Peri says goodbye to her mom...
The Sixth Doctor takes Peri to Earth's moon in the far future, where it's been hollowed out and made into a giant media centre. Everything that was ever recorded in Earth's history can be watched there. While the Doctor goes off to find a book that might save the universe from something, Peri decides to have a look at what's going on in her own time period. She immediately discovers that a very close family friend, Anthony Chambers, has been murdered.
The Doctor brings Peri back to her home in 1984 Baltimore so she can attend the funeral. She's greeted very coldly by her mother Janine, Anthony's best friend, who thought that her daughter was dead for four months. Janine and Howard had divorced in the meantime (after she accused him of murder), and she turned to the Chambers family for emotional support. After all, she'd similarly been there for Anthony when his own wife died, and Anthony's children — Kathy and Nate, now staying with Janine — are Peri's closest friends. But realising that her daughter is not only alive but now also plans to draw all the attention during the funeral to herself, Janine can only give Peri the cold shoulder. Peri breaks down into tears by Anthony's grave.
The Doctor, meanwhile, decides to investigate and soon discovers that the murder wasn't what it looked like at all. When he finds the accused, a grieving widower named Mr. Woods, at the police station, the policemen turn out to be mind-controlled. He and Woods escape and have a long, serious discussion about Woods' emotional state, and his grief over losing his wife — through which the Doctor makes him realise that it's their duty to find out what did happen.
While Peri struggles with her grief and her mother's extremely cold reaction to her return, she also finds out that her best friend Kathy has been having a much easier life without Peri around. Despite getting more and more emotionally broken, she agrees to watch a video recording of Anthony's last birthday together with Kathy, Nate and Janine. And, having a few years of TARDIS experience under her belt, notices that something's very wrong — there's a message tacked on at the end of the video, in which Anthony tells everyone he's being controlled. Janine is thoroughly disturbed by how mature and experienced her daughter is when it comes to danger. But after a quick attempt at explaining everything, the makeshift family agrees to folow Peri back to the Doctor.
Meanwhile, the Doctor and Woods realise that Cybermen are behind it all — specifically, Cybermen from the Doctor's own future. Their main agent is a partially converted Anthony. While Janine, Nate and Kathy attempt to cope with seeing him stumbling about, the Doctor finds the Cyberleader, who's badly damaged and trapped inside a stolen TARDIS found "on a burning planet". He needs the Doctor to steer it, to convert the dead into Cybermen, and to change Earth's future forever. The Doctor is definitely not over his Cybermen guilt yet, and tries to explain what a horrible idea changing the future is.
Also, everyone keeps saying "8687"...
Anthony's children, Woods and Janine try to confuse his cyber-implants, using the video tape to remind him of who he truly is. It's enough to halt him while the Doctor talks to the Cyberleader, but Nate is very badly wounded in the process, and Woods is killed. The Doctor, who faces the idea of Nate being murdered just to convince him, begs the Cyberleader to reconsider. But the Cyberleader reveals that everything — the murder, the manipulation of the police force, Woods — was set up using their data surveillance, just to manipulate the Doctor into coming down to Earth and helping to restore the Cybermen.
The Doctor eventually relents. He sets about converting corpses into Cybermen and leaves them the technology so they can convert others. The Cyberleader makes the Doctor take him several months into the future of 1984, so he can see the glorious new future of the Cyber race... which the Doctor does. To be precise, he takes the Cyberleader to several months into the future of 1984 on Mondas. Where the Cyberleader is promptly carried off by commander Zheng to be repurposed. The Doctor (who, of course, didn't convert anyone whatsoever) wishes him a very Orwellian rest of his life.
In the aftermath, Nate is taken to a hospital and survives, if just barely. Peri and Kathy re-kindle their friendship, and Peri decides to stay home, instead of travelling with the Doctor. She wants to keep the rest of the Cyber-technology as a bit of a souvenir. Six is heartbroken by her goodbye, but realises that everything ends, no matter how much they love each other. Back on the moon, he looks in on Peri... only to see her standing by her mother's grave. While Peri was out enrolling in university again, Janine accidentally activated the Cyber-technology, which recognised her as an unauthorised user and self-destructed. Peri goes back to travelling with the Doctor, thoroughly broken.
The Reaping contains examples of:
- 10-Minute Retirement: Of the Tear Jerker variety. Peri leaves the Doctor after the events of this story then her mother dies because of a malfunctioning piece of Cybertechnology, and joins the Doctor once more, after that. But you probably already knew this.
- Ambiguously Gay: Lt Doyle, Mrs Van Gysegham thinks he's odd because he's 'never had a girlfriend'.
- Arc Number: 8687, the significance of which is not revealed until "The Gathering".
- Batman Gambit: The Cyberplanner killed people to near Peri's hometown in order to lure out the Doctor.
- Bigger on the Inside: Doubles as Foreshadowing.
- Bitter Almonds: How the Doctor knows Lt. Doyle is trying to serve him poisoned coffee.
- Brick Joke: The Doctor is still carrying the cup of coffee once they get to the graveyard.
- Call-Back: The Eighth Doctor did — does — eventually visit the Ice Caves of Shabadabadon, which the Fifth, Sixth and Seventh Doctor all had planned to once do.
- Call-Forward: The Cyberleader stole a TARDIS from a "burning planet"... presumably Gallifrey.
- Catchphrase: "That will be ... Excellent."
- Cloning Blues: Allan, all Allans, are cloned from one Allan, and they have been on the Gogglebox showcase for over 2000 years.
- Continuity Nod: The Doctor mentions having seen the way the Cybermen came to be.
- Downer Ending: After the Cybermen are defeated and Peri has decided to stop traveling with the Doctor and stay with her family, a leftover bit of Applied Phlebotinum blows up her house while she is out enrolling in university, killing her mother.
- Drives Like Crazy: Mrs. Van Gysegham, much to the Doctor's distress.
- Also a case of Women Drivers.
- Exact Eavesdropping: Peri listens in on a conversation where her best friend laments the fact she's returned..
- Hoist by His Own Petard: The Cyberplanner is dropped off on Mondas, where he gets recycled for parts by the original Mondas Cybermen.
- Human Resources: Well, it's a given with a Cybermen story, the real kicker is The Doctor's made to be thought that they're dead body parts.
- "I Know You're in There Somewhere" Fight: Peri and the Chambers kids try to appeal to the partially cyber-converted Anthony Chambers' memories of his human self, by showing him videos of himself and reminding him of the family's routines.
- Logic Bomb: The Doctor employs a small one to escape a controlled police agent.
- Make Wrong What Once Went Right: The Cyberplanner's plan.
- Mundane Utility: The Gogglebox can show you ANYTHING. Peri wants to use it to see what her friends and family at home are doing.
- Nanomachines: The Cybermen have started employing this in their technology.
- Older Than They Look: Daniel Woods, a pensioner, calls the Doctor a "Peculiar young man." the Doctor thanks him for the compliment.
- Omniscient Database: The Gogglebox is one, allowing users to access any recorded media from any point in history.
- Reality Ensues: This is pretty much "Reality Ensues: The Episode". Peri comes home only to discover that her mother thought she'd died, her mother and Howard have divorced over the fallout (she accused him of murder), and life without Peri has actually been easier for her friends and family in some ways. And then, once everything is resolved, Peri's decision to keep a bit of Cybermen technology as a souvenir makes her responsible for the worst thing that will ever happen to her, because it blows up and kills her mother, almost as an afterthought to the adventure. They're really not kidding with the title.
- Red Herring: The opening sequence has Peri saying goodbye to her mom in a very fond way. Turns out she didn't come back in the TARDIS to before her departure. She was planning on running away to Morocco for a while.
- The Scream
- Shout-Out: The Doctor mentions the The Pussycat Dolls and Police Academy as things Peri could experience with the Goggle Box.
- The Slow Path: Sort of inverted. Peri can't believe that it's only been four months since her mother last saw her, and doesn't have the heart to tell her mom that it's been years from her own perspective.
- Video Wills: Mr. Chambers leaves one for his children at the end of a home movie of his 40th birthday party, revealing that he was being controlled by the Cybermen and telling them to leave Baltimore.
- The Virus: The Doctor believes there is one consisting of Nanomachines.
- We Come in Peace Shoot to Kill
- What Have I Become?
- Will They or Won't They?: Peri enjoyed a lot of flirting with Nate before she became a time traveller. They sort of resume it during the episode, but Peri's a few years older and has seen an entire universe. And then Nate is moved to a hospital in a different city after Janine dies, Peri goes back to the Doctor, and they never see each other again.
- Kathy and Peri also always sort of hoped that Janine and Anthony would become a couple, but the two were more Like Brother and Sister.