The multiverse itself is shaped as an infinity sign, with two conjoined loops. One loop is "Ayewards", in which magic is common practice and easy to do, while the other is "Naywards", the worlds in which magic is nothing more than superstition, if not completely unknown. Our Earth is currently on the Naywards side, and seems to have been sliding back for a while. Keeping watch over the balance of magic, a group of persons of great power called the Magids have a great number of agents on each one of the worlds, Ayewards and Naywards alike.
Roddy lives on an Ayewards world in which the King of England and his court are the keepers of magic. Traveling with an appointed magician, called the Merlin, he strives to keep magic under check. However, during an important political meeting the current Merlin suddenly dies and things get complicated. Roddy, one of the kids travelling with the court, gets stranded and ends up uncovering untold magical power and a conspiracy that plans on taking over all magic. But who will believe her?
On Earth, Nick Mallory is searching for a way to travel across different worlds and unexpectedly finds one. It's not easy for him, however, as at first he thinks it is all a dream and his lack of regional customs puts him into deep trouble. While travelling he ends up making many enemies, and wandering around the worlds he ends up meeting with Roddy's uncle, a Magid, and figures that Roddy's world is in trouble. Now he has to help Roddy save her world while dealing with all the problems he seemed to collect on other worlds.
The Merlin Conspiracy shares a setting with Deep Secret, one of Diana Wynne Jones's novels for older readers. The second book is somewhat tamer than the first and can be enjoyed without having read the first, but some backstory may be missed (Deep Secret is, among other things, the story of how Nick Mallory learned of the Magids). It is also less definitely aimed at young adults; this is part of the reason it was not advertised as a sequel.
Tropes appearing in The Merlin Conspiracy include:
- Adults Are Useless: Averted and played straight at the same time. Most of the adults that Nick and Roddy try to enlist the help of are very powerful and very clever. Unfortunately they either refuse to help because they don't believe Roddy or are kidnapped. Also, several adults are very useful before their kidnapping, but aren't brought back to Blest until after all the action has taken place, Maxwell Hyde being the prime example. Romanov is the primary aversion, as he's not kidnapped (although does get very, very sick and almost dies at one point), and spends the climax of the story undoing Joel's binding spells on the kidnapped off-screen.
- Ax-Crazy: Older Japeth. Though both his and Joel's younger selves weren't above murder.
- Balancing Death's Books: Roddy's grandfather, Gwyn, the lord of the wild hunt, finally gets his revenge.
- Belligerent Sexual Tension: Roddy and Nick's POV sections are littered with each remarking on how attractive the other one is, while venting inwardly about how frustrating they are, and they passive-aggressively bicker a lot.
- Berserk Button: Don't laugh at Japeth.
- Big Sister Instinct: Roddy towards Grundo, crossed with Parental Substitute, to the point where it seems that her entire life revolves around protecting him. She can thank a glamour for that, and she does not take the revelation well.
- Bumbling Dad: Nick's. Despite being a famous horror writer, he absolutely does not understand his teenaged son.
- Canon Discontinuity: Sort of justified. The "Also by this author", "About the Author" and book blurbs seem to like to pretend that The Merlin Conspiracy is a stand-alone novel, completely ignoring Deep Secret. This, however, is a Really Bad Idea—because Merlin is very obviously written as a sequel (the references to Magids and Nick's home life make zero sense otherwise), and is much more confusing without having read Deep Secret first.
- Chess Master: Joel and Japeth, who mastermind the events of the book, across time and the entire multiverse.
- Cold-Blooded Torture: What Japeth wants to do to Nick. Instead, he settles for human sacrifice.
- Crapsack World: Nick wanders through several. Loggia City is probably the most crapsacky world with living people in it that we see. At the climax, all worlds get varying degrees of this, with magic being permanantly altered and causing chaos, though it's implied they get better.
- Crystal Dragon Jesus: One of the universes Nick pops through has Loggia City, which is run by the Prayermaster and the Lawmasters.
- Deadpan Snarker: Usually Nick, often as part of his Belligerent Sexual Tension with Roddy.
- Don't Fear the Reaper: Gwen ap Nud is actually quite a nice fellow. If you summon him up, he'll even warn you about how many summons you have left and the likely consequences. But if you do end up going over your number of summons...
- Easily Forgiven: Grundo, when it transpires that the reason that he and Roddy are so close is because he glamoured her into protecting him when they were small. Part of this is possibly because Roddy doesn't have much time to process this before the climax, beyond the initial breakdown, and he leaves shortly after with his father, Romanov. Plus, as Nick observes, they both genuinely needed a friend.
- Enfant Terrible: Joel and Japheth, who murder their teacher/guardian.
- The Izzies, who seemed to be your typical spoiled brats, but apparently genuinely ask Romanov if he can ensure their grandmother dies before one of them gets chucked out of the family home in accordance with their hereditary rule of three.
- Extreme Doormat: Grundo appears to be a variant on this, in that he lets Roddy do everything for him. As it turns out, he's quite capable on his own and originally glamoured her into protecting him when they were three.
- Fainting Seer: When the new Merlin is introduced to give a prophecy, he begins weeping and faints. The audience is unimpressed, and complain that they wound up with one of the 'weepy' kinds of seer.
- The Fair Folk: The little people. They're friendly enough, but they don't look at all like traditional fairies (the way they're described makes them seem catlike in appearance, and with backwards-bending knees), and they carry off a (very unpleasant, admittedly) girl at the end.
- Foreshadowing: How does Grundo pick up so fast that the Izzies have glamoured their mother and grandmother to get away with their behaviour, and weave a counter-spell? He's been doing something quite similar to Roddy all his life - though he, at least, has the decency to feel guilty about it.
- Hidden Depths:
- Grundo appears to be an Extreme Doormat who relies entirely on Roddy, with severe difficulties because of his dyslexia. He turns out to be a very powerful, very perceptive, and very subtle wizard - in line to be the next Merlin, in fact. This is not entirely surprising, considering that his father is Romanov, who is all of those things and more.
- The Izzies are apparently self-centred, spoiled brats. They've also been glamouring their mother and grandmother, both powerful witches, for years to get away with their behaviour.
- Hepzibah Dimber, Roddy's grandmother, is a vain, self-obsessed, and snobbish witch (whose tacky behaviour and style in turn triggers all the snob instincts in Roddy, who feels guilty about it). She is also exceptionally powerful and, magically speaking, usually quite perceptive.
- Meaningful Name: Roddy's grandfather Gwyn.
- Mirror Character: Grundo and the Izzies, both of whom glamour people close to them to get what they want - though the former at least has the decency to be ashamed of it, and having moderately understandable reasons (an abusive mother and a Big Sister Bully, for starters).
- The Multiverse: A primary feature of the story, with the ability to wander between worlds the main province of the Magids.
- Mundane Utility: Maxwell Hyde, a powerful Magid and traveller of The Multiverse, makes a lot of money as a novel writer in other worlds, using his experiences in his home world of Blest to provide flawless worldbuilding.
- My Beloved Smother: Roddy's behaviour towards Grundo tends towards this. It turns out that he glamoured her when they were three to behave like this, protecting him. She does not take the realisation well. Like, at all.
- Offing the Offspring: Sybil was going to offer Grundo up as the human sacrifice, until Japeth saw Nick.
- Parental Substitute: Roddy to Grundo, crossed with Big Sister Instinct, to the point where her entire life seems focused on protecting him. As it turns out, this is by design, thanks to a glamour he cast on her when they were three and maintained since, so she does everything for him (he at least has the decency to feel guilty about it). She does not take the revelation well.
- Save Both Worlds: More like save all worlds.
- Self-Made Orphan: Joel and Japeth. (Although technically he was just their teacher/guardian).
- Stable Time Loop: Time doesn't work the same way in all the worlds Nick visits, and it turns out that one of his actions while traveling from world to world was the start of a chain of events leading to the event which set him traveling from world to world in the first place.
- The Stoic: Romanov, who rarely expresses much in the way of emotion. This is something he has in common with his son Grundo.
- Talking Animal: Mini, the elephant. Mini cannot actually speak; Nick just has a mental connection with her, and some other animals.
