Sallowed Blood — Stuart G. Yates

In the dark corners of a castle deep in the Bavarian Alps, a secret awaits Daniel Stone.
After inheriting the castle from his grandmother, Daniel and his father travel to Bavaria. They soon notice a dark presence in the old stronghold; strange animal-like noises are emanating from the depths beneath the castle, and someone, or something, seems to be be following their every move.
After things spiral out of control, Daniel and his father receive unexpected help from an old relative, who tells them of the dark secrets the castle holds. But even with the three of them, will they be able to discover the centuries-old mystery that lie buried, or will darkness claim them all?