A surprisingly engaging piece of steampunky fantasy adventure, A Darker Shade of Magic takes place in a universe in which there are four Londons in four worlds, sitting next to each other like the pages of a book. Grey London is our London, largely magic-less; Red London is Kell's London, a thriving city where magic reigns and the air smells of flowers; White London, a harsh and terrible place whose citizens are starved of magic, bleeding anyone unlucky enough to stumble in; and Black London, sealed off forever amid dark rumours of magic gone horribly wrong, magic that has consumed and destroyed the people of the city.
Kell is an Antari, one of the few magicians left with the power to move between the worlds since they were sealed off from the plague of Black London. He carries messages for the king and queen of Red London to the rulers of the other two Londons, this being the only interaction allowed between the worlds. But he also runs a clandestine smuggling operation, which is how he ends up with a forbidden relic from Black London, a talisman of corrupting magic which threatens all the remaining worlds. With the help of Lila, a desperate and talented thief from Grey London, he resolves to return the talisman to Black London; but the power-hungry rulers of White London would much rather have it for themselves.
I'm not sure that all the world-building entirely makes sense (why do the rulers of the Londons need to keep sending messages to each other when there's no apparent political benefit, for example?), and at least one promising thread is dropped (what happened to Ned?), but A Darker Shade of Magic was a good, solid read which got unexpectedly touching towards the end. Lila in particular is awesome, preferring long black gentlemen's coats to dresses, refusing to be patronised or talked down to, stealing whatever weapons she can get her hands on, and generally kicking ass. She's also distinctly amoral - she loves thieving and takes pride in being good at it, and she doesn't conceal her willingness to resort to violence. Actually, Kell pales in comparison to Lila, though even he isn't exactly a moral paragon, being a smuggler and a man who kills for revenge.
The plot isn't particularly strong, being essentially a journey across the four Londons held up by various obstacles (it feels vaguely like a video game, actually), but the vividness of Schwab's characters, her magic system and her worldbuilding make up for it. This is a violent book, but it doesn't feel dark; it's an amoral book, but it doesn't feel gratuitous. I enjoyed it - it's imaginative, well-paced and full of feeling.
(Just to register the one off note I felt was a bit male-gazey, especially as it's from the point of view of a woman: "Had Lila been a man, and the ships fair maidens guiding up their skirts, she could not have wanted them more." Um...because women don't experience sexual desire? I just felt that sentence was unnecessary. This isn't symptomatic of the whole book, though.)