In a world where the kingdoms are built amongst the sky, The Mariposa are an elite assassin group that have a mission to undermine the corrupt government. The nobility of the seemingly peaceful kingdom of Arcelia holds deadly secrets and a sinful past. However, Maeve learns that the Mariposa may not be as virtuous as they seem either, when she is commanded to kill the person she least wants to. Drawing the line on this mission, she must choose which empire to topple. The Mariposa? Or the Castle?