And that was how Beau and I found ourselves at the rear of the procession into the city.

Le Présage was unlike anything I’d ever seen. Just as I’d suspected, the melusines lived like magpies, building their homes from the remnants of sunken ships, from coral, from stone, hoarding sunken treasure to decorate their windows and lawns. A weathered marble bust sank deep into the silt of a kelp-filled garden at the edge of the city. The owner had affixed diamonds to each eye. Farther in, officials ushered melusines to the side of a bustling thoroughfare. Instead of brick or cobblestones, the road had been paved with mismatched coins—gold, silver, and bronze couronnes, as well as foreign coinage I didn’t recognize. The occasional gemstone. An errant shell.

“Is it always this . . . crowded?” Beau asked, brows raised. Scores of melusines gathered to watch us pass, their eyes luminous and skin lustrous. Many wore gowns hundreds of years out of fashion—ostentatious and ornate—while others, like our guards, wore nothing at all. A merman with a bone necklace and pearl hood winked at me from afar. His companion had painted her entire body gold, donning only a fork in her intricately braided chignon.

The only thing every melusine had in common, it seemed, was their legs.

“We have not walked for many years,” Aurélien said as means of explanation.

From around the bend of the street, a team of sienna-colored octopi surged into view, pulling a gilded carriage behind. Except its paint had disintegrated in the salty water, and its wood had mostly rotted, caving in half the roof. Still, the melusines nearest it clapped gleefully, and the couple inside—one wore a monocle, for Christ’s sake—waved as if royalty. And perhaps they were. Perhaps kings and queens in the world below owned octopi and carriages. Perhaps they also sewed shark teeth into veils and wore golden cutlery in their powdered wigs.

The entire city glittered with the air of ludicrous opulence gone to seed.

I adored it.

“I want a wig.” I couldn’t see enough as we marched past little shops of stone with planter boxes of red algae. One melusine walked his pet spotted turtle on a gold-threaded leash. Another lounged in a claw-footed tub at the street corner, pouring water from a pitcher onto her legs. They transformed back into obsidian fins before our very eyes. Merchants hawked wares of everything from conch fritters and crab legs to oyster-and-pearl earrings and music boxes. The light of the sea stars undulated eerily across each face, the only illumination in the entire city. “Why do melusines own wigs?”

“And gowns?” Coco asked, eyeing the couple nearest us. They both wore heavy trains of brocade velvet and . . . corsets. Just corsets. No bodices. No chemises. “How do you wear them with fins? Wouldn’t skirts weigh you down in the water?”

“Can a melusine drown?” I asked curiously.