Let me begin by stating that this is a perfect book.
I don't say this lightly. It's perfect in the way that excellent clockwork is perfect: intricate, precise, and hiding all its marvels in plain sight. Imagine a clear box full of interlocking gears and springs and pulleys — you can follow all their movements, trace every tooth's bite, but what it produces in chimes or bursts of colour and light are mysteries to surprise and delight you.
Caverna is an underground world of crafts so masterful they're also magical. Wine can improve or obliterate your memory, Perfume controls thoughts, and Cheese can give you visions of the future — or explode. But most curiously, the people of Caverna are born with faces that are blank canvases; they must be taught expressions by Facesmiths, choosing them out of catalogues and paying handsomely for the service. Thus the wealthy can call on a large variety of Faces to express (and conceal) their thoughts, while the poor are taught only faces that the wealthy want to see: faces of cheerful subservience and quiet deference.
Neverfell has no Face and no memory when Grandible, a master cheesemaker, finds her in a vat of curds and makes her his apprentice. What she does have is a boundless energy, profound curiosity, and a fascination with machinery of which Grandible despairs. She longs to explore the world beyond his tunnels, but something about Neverfell's face is terribly wrong, so wrong that Grandible has her wear a mask whenever there's any chance of someone seeing her. For seven years, he's kept her hidden from the rest of Caverna, where courtiers play at murder as easily as cards — but when a rabbit that refuses to be milked escapes through a crack in a wall, Neverfell chases it, tumbling headlong into a web of plots within plots all rooted in her vanished history.
This is a book that writes the story of itself into its smallest corners. The prose is so purely delightful that I kept folding down pages to return to. I laughed at exceptional turns of phrase, only to find myself tearing up a few passages later, as if the book were itself a catalogue of Faces for me to try on. The magical crafts are endlessly inventive and full of startling enchantment: "The Addlemeau still needed to develop its undertones of vanilla, and the Smogwreath had not overcome its fear of strangers," while the eccentric Cartographers speak of "melancholy basalt" and reckon silver by sung degrees.
To identify any aspect of this book is necessarily to sing its praises. The characters are engrossing, their relationships moving and lovely; Neverfell's innocence and capacity for love and kindness carry her through enormous social upheavals, while the mystery of her lost memory burns hot and furious and hidden inside her. But above anything else what astonished me about A Face Like Glass was its construction, its pure perfect pace, the mechanical gravity of its plot moving through its beat with meticulously crafted finesse.
As the book teeters on the brink of its denouement, Neverfell says "A machine is sort of like magic. You spend ages planning it out, and put all the cogs in place, and then bing! you pull a lever and away it goes. And the amazing bit is that the person who pulls the lever to start it doesn't need to understand how it works. They don't even need to know what's going to happen."
A novel is sort of like a machine — and A Face Like Glass is everything like magic.