anyway,

the bull mask suddenly made me remember a book a while ago called the magus
by john fowles

a young englishman, nicholas urfe, accepts a teaching position on a greek island where his friendship with the owner of the islands most magnificent estate leads him into a nightmare.

as reality and fantasy are deliberately confused by staged deaths, sensual encounters, and terrifying violence, urfe becomes a desperate man fighting for both his sanity and life.

it's been years but i distinctly the protagonist coming across people wearing animal masks as he gets more deeply involved with the estate's owner, who's a mysterious wealthy greek named conchis. as the title suggests the book has a lot of occult themes.

published in 1965