This episode provides the beginning of two story arcs: the Sixth Doctor's dealings with the Forge and the Character Development of Evelyn Smythe, and the Seventh Doctor's later encounter with Nimrod and the subsequent Story Arc of companion Hex.
The Sixth Doctor takes Evelyn to South East London for (allegedly) the best Chinese takeaway in the universe, only to unexpectedly blunder into a trail of half-eaten animals leading into a neighboring alleyway just outside the Dusk, a popular local casino. There, they find that one of the casino workers has been shot in the chest with a crossbow, and though they arrive too late to get a good look at his attacker, the Doctor is eventually able to convince the casino's owners, London Gangster Reggie Mead and Amelia Doory, to let them help the unfortunate worker before he dies of his injuries. Unfortunately, by the time they get down to it, the worker dies - via swelling up like a balloon and exploding.
As it soon becomes clear, Reggie, Amelia, and a good deal of their employees are genetically-modified test subjects escaped from a government experiment, and are attempting to find a cure for their conditions - hence why the Dusk is outfitted with a fully-equipped laboratory... and why violent casino patrons have a tendency to vanish during the night. Unfortunately, Amelia's attempts have all ended in failure; worse still, the modified refugees are being hunted by a mysterious killer known only as Nimrod - the same man who shot the casino worker earlier.
While the Doctor discusses the situation, Reggie catches one of the human casino waitresses snooping around his files, and is only prevented from getting violent by the timely arrival of Evelyn. The waitress, Cassie, is reluctant to put her trust in Evelyn, but after being rescued from one of Nimrod's crazed former victims and helped back home, she gradually opens up to the fact that she's being blackmailed: having discovered that the casino waitress is a young mother, Nimrod is threatening to murder Cassie's son Tommy unless she agrees to act as his spy inside the Dusk. So far, she's managed to find a coded journal by a World War I-era scientist, but little else. Worse still, Nimrod pays a visit later and leaves Cassie seriously hurt, forcing Evelyn to take her back to the Dusk for treatment.
Back at the casino, the Doctor is sympathetic to Amelia's plight and agrees to help find a cure for her fellow sufferers, seemingly finding great success in isolating the nanites used in Nimrod's crossbow bolts. However, everything changes when Nimrod himself pays another visit to the Dusk, killing one of Reggie's business partners in the process: revealing blood packs in the dead man's briefcase, Nimrod draws attention to the fact that Reggie doesn't possess a reflection, and the Doctor finally realizes that the people he's been trying to help are actually vampires - humans genetically altered with samples taken from the Time Lords' greatest enemies.
Though Nimrod is eventually forced to retreat by a shotgun-wielding Amelia, the Doctor is not at all happy to discover that he's been helping vampires all along. Blinded by Fantastic Racism, the Doctor refuses to explain the situation when Evelyn and Cassie return to the Dusk for treatment, and begins shutting his companion out on the grounds that he knows more about the situation than anyone else. However, Amelia is eventually able to sweet-talk him into helping them again, reasoning that vampires aren't Always Chaotic Evil.
Through a combination of sources - ranging from Amelia's explanation to the coded journal that Evelyn brought back - the Doctor learns that the Dusk's vampires were created during the First World War by a covert government organization known only as the Forge. Having somehow acquired a sample of vampire DNA, they were using it to convert prisoners, incurable patients and other disposable individuals into super-soldiers to tip the war in the favor of the British. Their reluctant creator, one Dr William Abberton, was careful to engineer the newly-created vampires with varied weaknesses - some to sunlight, some to water, and some even to helium - but that ultimately did little to prevent the subjects from rebelling: breaking out of captivity in 1915, they shot Dr Abberton dead and escaped into Britain's criminal underworld.
Feeling guilty over his Fantastic Racism, the Doctor agrees to find a cure for the vampirism: analyzing Nimrod's nanites, he soon finds a means of reprogramming them, guaranteeing that they'll be able to convert the vampires back into ordinary human beings if properly instructed. Unfortunately, with Cassie and Evelyn left out of the loop, they're caught by surprise when Reggie bursts in and tortures Cassie almost to death for working with Nimrod; by the time the Doctor demands an explanation, Amelia's already stolen his research. It turns out that her goal had always been to figure out how to create more vampires, for the Forge had been very careful to ensure that the subjects could not reproduce on their own; with the Doctor's findings, Amelia is now dead set on using the newly-perfected Twilight Virus to make all of humanity into vampires, starting with Cassie.
While the Doctor is locked away in a cell, Cassie is converted into a vampire; with some coaching from Amelia and Reggie, she seemingly embraces the Horror Hunger and demands to be set loose on Evelyn. Instead, she turns on Reggie, beating him to a pulp and impaling him with Nimrod's crossbow bolt, bursting the wannabe-gangster like a balloon; in the aftermath, she helps Evelyn escape.
Meanwhile, Nimrod unexpectedly breaks the Doctor out of his cell. It turns out that Nimrod is actually Dr Abberton, having converted himself into a vampire to survive the gunshot wounds; over the decades, he's been augmented with additional gene therapy, bionic augmentation, and just about anything else the Forge can outfit him with to make him a more effective killer. Now he's serving as the Forge's muscle in the field, and is dedicated to eliminating his creations at any and all cost - including a tentative alliance with the Doctor. Delving into the bowels of the Dusk, the two of them discover a prison for specially-bred human slaves, mindless blood-banks intended to feed the appetites of Amelia and her cronies. Here, Nimrod ends up getting shot with his own crossbow by Amelia, and though he survives, he remains behind to plant a bomb in the blood-farm while the Doctor tries to stop Amelia from releasing the Twilight Virus on London.
In the end, the Dusk is destroyed when the bomb detonates, and the Doctor is able to tackle Amelia into the Thames before she can complete her plans, barely managing to stop her vial of the virus from breaking. However, Amelia's body is not found, and Nimrod manages to escape alive. Elsewhere, Cassie declines to become a companion on the grounds that she's too dangerous to be anywhere near other human beings, so at her request, the Doctor drops her off in Norway during the Polar Winter and promises to come back for her once he's found a perfect cure. And he will, soon enough.
Tropes
- Aborted Arc: Amelia's fate is left deliberately ambiguous which gives the impression that there was at least a potential plan for her to return but the character was ultimately never brought back, later stories instead focused more on Nimrod and Cassie (and her son). As such it's probable that by the end she is in fact dead despite Never Found the Body being in play.
- Angrish: Reggie unleashes some particularly vicious gibberish while smashing up his office.
- Body Horror: Anyone who happens to meet Nimrod will end up like this.
- Cat Scare
- Cold-Blooded Torture: Cassie's crying will haunt you.
- Continuity Nod: The Doctor mentions meeting Harry Houdini, and that he once visited the court of Kublai Khan. Evelyn also tells the Doctor that fishing him out of the River Thames in front of the Tower of London is becoming a habit.
- Cyborg: Nimrod
- Fantastic Racism: The Doctor dislikes vampires, because where they came from.
- Fin Gore: Reggie breaks all the fingers on a reluctant business partner's hand.
- Foreshadowing: "Zagreus sits inside your head, Zagreus lives among the dead, Zagreus sees you in your bed and eats you when you're sleeping."
- Gone Horribly Right
- Implacable Man: Nimrod can take a shotgun blast. And the explosion.
- My God, What Have I Done?
- Mythology Gag: The Doctor is about to ask Evelyn if she's ever been to Blackpool right before he steps in a dead cat.
- Nanotechnology
- Never Found the Body: Amelia
- Nice Job Breaking It, Hero: The Doctor is tricked into finding a way for the Vampires to transform more humans.
- Nightmare Face: Reggie destroys Cassie's face. She finds out.
- Ninja Pirate Zombie Robot: Nimrod is a crossbow-wielding cyborg vampire zombie mad scientist.
- Older Than They Look: The vampires, natch.
- "Open!" Says Me
- Our Vampires Are Different: While they conform to some classic vampire tropes, they don't all share weaknesses, and they cannot reproduce by biting. Rather, they inject their victims with a syringe.
- People Farms
- Percussive Therapy: Enraged at having his ego punctured by the Doctor and under severe stress by the threat of Nimrod, Reggie takes a baseball bat to a large chunk of his office - which he excuses as "letting off steam."
- "Pop!" Goes the Human: The fate of Eddie. And Reggie.
- Rage Breaking Point: After a day spent being menaced by Nimrod, seeing his lieutenants murdered, losing out on a critical deal with a group of other vampires, and catching Cassie in the act of spying on him, what really makes Reggie lose his temper is a single smartass remark from the Doctor.
- Safely Secluded Science Center: The intro takes place in an isolated military lab hidden away in a frozen, moor-studded wilderness; as it quickly becomes apparent, it's run by the Forge as part of a WWI-era initiative to create vampire super-soldiers. Unfortunately, the isolation of the base works against it when the test subjects break out, killing the doctors and fleeing the area en mass.
- Self-Destruct Mechanism
- Sequel Hook: See trope below.
- The End... Or Is It?: Amelia has never been found and presumably knows how to make more of the virus, Nimrod is alive, and he knows of Cassie being a vampire, just not where either of them are.
- The Undead: Not just vampires either
- Unhand Them, Villain!: "Put Nathaniel down, you said?"
- Vehicular Sabotage
- Viral Transformation: The plan of the Vampires.
- Was Once a Man
- Weakened by the Light: Some of the Vampires purposefully (see just below).
- Weaksauce Weakness: Built in to the vampires on purpose.
- What Happened to the Mouse?: What happened to Cassie's son? (As we find out in later episodes, he grows up to be Hex.)
- Who Wants to Live Forever?: Amelia says this is one of the bad things about being a Vampire. She turns out to be lying.
- You Monster!
