Kell can walk between four different Londons, and the price of that ability is written right into how Schwab stages every single crossing: he has to bleed for it. Not metaphorically. Every jump between Red London, Grey London, White London, and the sealed-off ruin of Black London costs him blood on his palm and a specific, physical toll on his body, and that one rule does more worldbuilding in a paragraph than most fantasy novels manage in a chapter. You feel exactly what it costs to move between worlds, which means you feel exactly what's at stake when someone forces Kell to do it more than he should.
The four Londons themselves are the real showpiece here, and Schwab resists the urge to just list off differences between them. Grey London is our world, magic-starved and gray in more than name, a place where nobody remembers what the other cities have. Red London is vivid and thriving, magic woven into daily life the way electricity is woven into ours. White London is a starved, vicious place where power is the only currency and the wrong smile can get you killed, ruled by twin monarchs who treat cruelty as a management strategy. Black London barely exists anymore, mentioned mostly in the hush of people who remember why it was sealed off, and that silence does more to sell its horror than any flashback could.
Delilah Bard is the character who keeps the book from tipping into pure travelogue. She's a thief with a taste for other people's coats and a hunger to be anywhere but her own life, and her introduction, robbing Kell blind before saving him from an assassination attempt, tells you everything about how she operates before she's said a hundred words. Her chemistry with Kell isn't romance so much as two people recognizing a matching kind of recklessness in each other, and Schwab is smart enough to let that stay prickly rather than rushing it toward anything softer.
Where the book runs into trouble is pacing in the middle stretch, where court intrigue in White London slows the momentum the opening chapters build so well; a few readers have found that patch a genuine drag before the plot regathers itself. It's a fair critique of a book that otherwise moves fast, and it doesn't undo the tension Schwab has built around the central threat: a piece of Black magic that shouldn't exist crossing into a world it can unravel. The stakes never feel abstract, because Schwab keeps grounding them in what a corrupted world actually looks like on the ground, in the people who suffer first.
Why you should read
- Readers who love inventive, rule-based magic systems
- Fans of portal fantasy with real worldbuilding stakes
- Anyone who wants a prickly, slow-building central duo
- Readers starting a series they can binge across sequels
What to expect
- Four distinct parallel-world Londons, each vividly rendered
- A blood-price magic system with real physical cost
- A slower middle stretch of court intrigue
- Fast-paced adventure plotting once the threat surfaces
- The first book of a multi-volume series
By the time Kell and Delilah are racing to keep that magic from spreading between worlds, the book feels like a genuine adventure in its own right, not just a setup for volume two. Four cities sharing one name and almost nothing else is a wonderfully strange central image, and Schwab never lets you forget how fragile the walls between them really are.
