The Origin of Evil Spirits: The Reception of Genesis 6:1-4 in Early Jewish Literature

How do we account for the explosion of demonic activity in the New Testament? Archie T. Wright examines the trajectory of the origin of evil spirits in early Jewish literature. His work traces the development of the concept of evil spirits from the Hebrew Bible (Genesis 6) through post biblical Jewish literature.
I would in fact recommend this book, not because of the answers it gives, but the questions it raises. Philip R. Davies in Journal of Semitic Studies 55 (2010)
This work is marked by several strengths. First, Wright shows an impressive command of the primary and secondary literature. Second, this writer appreciates Wright’s tendency to express cautious conclusions regarding historical and source-critical matters. These qualities are especially helpful in a work dealing with the reception history of a given text. Third, Wright has an extremely helpful discussion of the identity of the nephilim of Gen. 6:4 (80-83). Mark D. Owens in Faith & Mission 24 (2007), pp. 68-70