Aelia Astor is a Sunkeeper. The ability to control light runs deep in her family's blood, descended from generations of nobility. Another power lurks in the darkest depths of the nation. Shadowseekers are highly feared; their ability to manipulate the night is a danger to those in power. They must be controlled. But Aelia makes a terrifying discovery. Her abilities go far beyond the divisions between day and night, and this makes her dangerous. The shadows beckon and Aelia must follow, no matter the cost.