Teylin Walker, fresh from an audition in LA, rides her bicycle smack into an invisible obstacle. A silver-haired, blue-eyed boy suddenly materializes-only to vanish again. Tey manages to track him to a warehouse, where she sees a group of imprisoned children with the same eye and hair colors. Their captors grab Tey as well and take them all to Los Sueños, an archipelago somewhere in the Pacific. Luckily, bounty hunters rescue the would-be actor from the Coterie, the criminal organization holding her captive. But getting back to the U.S. isn't easy. Los Sueños is a country whose king has intentionally isolated it from the rest of the world. Her only option, it seems, is paying thousands of dollars to take a sailor's spot on a ship. The bounty hunters' leader, Rob Stryker, who prefers the nomenclature "fugitive recovery agents," lets Tey help in chasing down Coterie members. It's precarious work, but splitting this bounty-and future ones-will fund her trip home. What the Coterie truly wants are all of the silver-haired children, aka the shadowborn. But the more Tey encounters shadowborn, the more she sympathizes with them, especially since the king wants them "eradicated." Lending support to these unusual kids will put her in conflict with Rob and the other agents, making the prospect of escaping Los Sueños even less likely. Alder sublimely casts this story's archipelago as a place entirely separate from the contemporary world. Its limited modern conveniences are sporadic, like running water and electricity. Cellphones don't work, and Tey sees a kitchen that "recalled a Victorian mansion from a school field trip." The titular characters have few appearances, unfortunately, though readers do get to see their powers, from telepathy to healing. Alder's concise prose works well to heighten the drama: "Heart hammering, I stopped in my tracks and squinted at the darkness that seemed unusually dense. The shadows rose off the ground, shielding the girl with a black vapor. I took a couple of steps back, my skin cold." The shadowborn are also steeped in mystery. How they become that way is unknown, and the children have no memories of their pasts. The action comes primarily from Tey and the agents' battling the Coterie.