Twin sisters, both on the run, but different as day and night. One, a professional rogue, searches for a fabled treasure; the other, a changeling, searches for the truth behind her origins, trying to find a place to fit in with the realm of fae who made her and the humans who shun her.  Iselia "Seelie" Graygrove looks just like her twin, Isolde... but as an autistic changeling trying to navigate her unpredictable magic, Seelie finds it more difficult to fit in with the humans around her. When Seelie and Isolde are caught up in a heist gone wrong and make some unexpected allies, they find themselves unraveling a larger mystery that has its roots in the history of humans and fae alike.  Both sisters soon discover that the secrets of the faeries may be more valuable than any pile of gold and jewels. But can Seelie harness her magic in time to protect her sister, and herself?