Blood Promise Book by Richelle Mead

In "Blood Promise," Rose Hathaway, a dhampir and guardian-in-training, sets out on a perilous journey to fulfill a promise she made to her true love, Dimitri Belikov. After a traumatic event, Dimitri has turned into a Strigoi, the most dangerous and evil type of vampire. Consumed by guilt and determined to end Dimitri's unholy existence, Rose leaves St. Vladimir's Academy and travels to Siberia, where she believes Dimitri is hiding.

As Rose ventures into the heart of Strigoi territory, she faces numerous challenges, including dangerous encounters with both Strigoi and fellow guardians. Along the way, she uncovers shocking truths about the Strigoi and the nature of their existence. Rose must confront her own inner demons, make difficult choices, and navigate the complexities of the vampire world to fulfill her promise and protect those she cares about.

"Blood Promise" is a compelling installment in the "Vampire Academy" series, exploring themes of love, sacrifice, and the consequences of choices in a world filled with supernatural dangers.