Blood Eagle by John Washbourne

Blood Eagle is a horror novel drawing on ancient Norse Myth and Russian legend, set on a remote Irish island in the late 1960s. Light house men save a young woman washed ashore in a storm. But the young woman is not what she seems. Soon they and the islanders are faced with the young woman's supernatural pursuers. They are trapped inside the lighthouse with an ancient evil, while outside wait the most feared warriors in history – a thousand years older: a thousand years more deadly