Diana Bishop (Palmer) is an American professor of history from Yale visiting a college at Oxford in the UK. There Diana soon stumbles upon a bewitched book in the Bodleian Library. Herself a witch by birth, Diana has refused to do magic for years, but is forced to face it again because of the secrets this book holds. She receives help from the mysterious vampire and geneticist Matthew Clairmont, in spite of the mutual antagonism between their people. While working together, they strike to uncover the book's secrets and protect it from the threats in the world of magic.
The series had three seasons, covering the events of the three novels in the All Souls trilogy.
Examples:
- Adaptational Diversity: In the TV show, Em is a black woman, descended from Tituba. Agatha and Nathaniel Wilson are also black.
- Age Lift: In the books, Matthew's sire Ysabeau looks slightly younger than he, but here she looks middle-aged. Probably to make it less confusing for viewers that a man Matthew's apparent age is calling her "mother".
- Word of God from Deborah Harkness explains that she imagined Lindsay Duncan as Ysabeau and that all the tragedies she has endured have aged her, even as a vampire. In the books, when Ysabeau refers to Diana as her daughter-in-law in public, Diana lampshades this by saying, "Second marriage, younger wife", as Ysabeau looks younger than she and Matthew.
- Black Dude Dies First: In the books, Matthew kills Gillian Chamberlian first, but her fate is left ambiguous in the series. In the series, Diana kills Juliette Durand, a mixed race vampire, and Emily Matther, Diana's aunt (a Black woman in the adaptation) is the next to be killed.
- Dark and Troubled Past: Diana's parents were killed by muggles who'd found out they were witches. Since then, she's refused to use magic. Until we find out that it was actually witches who killed them and covered it up.
- Daywalking Vampire: All vampires in this universe appear to be completely unaffected by sunlight, going about during the day freely.
- Does Not Like Magic: Diana's refused to use magic ever since muggles killed her parents over having it.
- Friendly Neighborhood Vampire: Matthew. He appears to refrain from drinking human blood at all, and is never anything less than a kind man who's a proper English gentleman.
- Great Big Book of Everything: The Ashmole Manuscript, also called the Book of Life. It contains all magical secrets of everything.
- Identical Grandson: Aisling Loftus plays Sophie Norman Wilson and her ancestor Susanna Norman
- Interspecies Romance: Diana starts one with Matthew. It turns out this violates the Covenant, a treaty between witches, demons and vampires which forbids such relationships due to fears it would upset the balance of power between them.
- Benjamin, Matthew's vampire son has one with Janet Gowdie, a witch and produced Bright-born children.
- Lipstick Lesbian: Diana's lesbian aunts are indistinguishable from other middle-aged women aside from their sexual orientation.
- Living MacGuffin: The Book in some ways. At least, it seems to make decisions about who gets to find it and who doesn't.
- It also comes alive when it merges with Diana at the end of the third book.
- The Magic Goes Away: Magic is fading from the world, with witches' spells no longer nearly as powerful, demons going mad increasingly and vampires unable to create more of their kind. Matthew states that if this happens, the humans will eventually notice it and find the world entirely dull.
- The Magic Comes Back: Or, that's the plan anyway. With The Book in the right (or wrong) hands the magic that's all but vanished could be brought back.
- Masquerade: Witches, demons and vampires all keep themselves hidden from normal humans. Diana is always keen to assure others no muggles saw when she accidentally did magic.
- Ouroboros: The de Claremont family sigil contains one.
- Our Vampires Are Different: They look indistinguishable from humans ordinarily, are unaffected by sunlight, don't age, can reproduce, cast reflections and don't have any aversion to holy items, have superhuman strength and speed and turn others by giving them some of their blood.
- Our Witches Are Different: Witches are another species distinct from humans in the series. People must have one witch parent at least to do magic. However, they still look the same.
- Pining After Protagonist's Parent: Peter Knox carried a torch for Diana's late mother Rebecca, later confirming he was in love with her when Satu asks. He's initially warm towards Diana due to her reminding him of Rebecca, but he quickly becomes antagonistic due to being fixated on gaining access to her powers which was also how things ended with Rebecca. As Satu states, Knox may have loved Rebecca but he loved her power more and he was the one who killed her and her husband for defying him. Knox says he blames Diana's father for leading Rebecca astray and causing her death, and clearly holds his rival in contempt even though he's been dead for years.
- Really 700 Years Old: Matthew estimates he was born about AD 500, and became a vampire in around 537, making him over 1500. Physically, he's 37.
- Rule of Three:
- The Congregation is a governing council consisting of three members of each of the three species (vampire, witch, and demon).
- In season one, Diana spontaneously manifests control over the elements on three different occasions: first, she summons wind, then rain, and finally fire.
- Shout-Out: The title is related to The Discovery of Witches by real witch hunter Matthew Hopkins, explaining witches supposed characteristics along with how they could be hunted down.
- Token Human: For Diana and her family, it's her friend Chris. For Matthew and his family, it's Ernst (Verin's mate) and Phoebe (until she becomes a vampire).
- Vampire Bites Suck: There is nothing romantic about being bitten by a vampire here. It's shown as causing realistic pain, and leaves a victim greatly weakened assuming they survive at all.
- Vampire Procreation Limit: Vampires can turn dying humans into vampires via a blood exchange; however, it doesn't work on humans that are already dead and they also have do transformations in a way that doesn't threaten The Masquerade (Marcus gets chastised for trying to turn his surgeon friend after he's fatally struck by a car in broad daylight, even though Marcus argued there was no one about and he couldn't just let him die). Another huge complication is that in the past fifty or so years, most vampires' attempt to make more of their kind has failed, with the humans just dying instead even if the exchange is completed in time; this is linked with the decline of magic in the world. Matthew de Clermont and his 'siblings' have been researching a way to resolve this problem.
- Vegetarian Vampire: Matthew only appears to feed on animals, along with the rest of his family. An exception is when he attacks Gillian.
- Voluntary Vampire Victim:
- Jack and other vampires have humans who allow the vampire to feed on them in exchange for money and other favors.
- Diana lets herself be bitten to save Matthew's life after Juliette attacks him.
