Khostrov's Heart.

There is a dark secret in the Khosrov Forest that dates back centuries. Iago has long since found the chest containing the heart of king Khosrov Kotak, hidden in the rocks as the source of the forest’s life force. However, it remains closed to him, as it can only be opened with the blood of a royal heir. From that moment on, Iago and Marusik are doomed to wait, searching for the only one through whom they will be able to open the chest and finally seize the power and authority of the forest.