Grave of Thorns (Greatcoats, #5.3)

The price of betrayal...

Murielle de Vierre was once the King's Thorn, a loyal member of the legendary swordfighting magistrates known as the Greatcoats. But a single poor choice turned her into a traitor and set her on a path that led far from the ideals to which she'd once held. Now she wanders alone, disgraced and despised, searching for the road home.