The Fiery Heart (Bloodlines, #4)

The Fiery Heart is the fourth book in Richelle Mead's Bloodlines series and was released on November 19, 2013. It is told from both Adrian's and Sydney's perspectives. As from the start of the series, Sydney Sage is an Alchemist who been assigned to protect the Moroi princess, Jillian Mastrano Dragomir, from the assassins who would like to overthrow Vasilisa (Lissa) Dragomir, the Queen of the Moroi, from her throne.