Splinters of scarlet

"In nineteenth-century Copenhagen, an orphaned seamstress goes to work for a retired ballerina and uses her magic to investigate her father's mysterious death while working for the same family years ago"--
For Marit Olsen, magic is all about strategy. It flows freely through her blood, but every use leaves behind a deadly, ice-like build-up within her veins called the Firn; a Firn build-up killed her sister. Eve, a fellow orphan whom Marit views like a little sister, is adopted by the wealthy Helene Vestergaard. Marit's father died while working in the Vestergaards' jewel mines, and she decides to use magic to secure a job as a seamstress in the household. Soon she finds herself in the middle of a treacherous deception that goes all the way up to the king of Denmark. Magic may be the only thing that can save her-- if it doesn't kill her first. -- adapted from jacket