A Dark Matter by Peter Straub

A Dark Matter is a horror novel told from the perspective of different individuals who were lured by a guru years earlier to a ritual in a meadow. Someone was gruesomely killed there, and the individuals try to come to terms with what happened as the story unfolds for the reader.

The charismatic and cunning Spenser Mallon is a campus guru in the 1960s, attracting the devotion and demanding favors of his young acolytes. After he invites his most fervent followers to attend a secret ritual in a local meadow, the only thing that remains is a gruesomely dismembered body -- and the shattered souls of all who were present.

Years later, one man attempts to understand what happened to his wife and to his friends by writing a book about this horrible night, and it’s through this process that they begin to examine the unspeakable events that have bound them in ways they cannot fathom, but that have haunted every one of them through their lives. As each of the old friends tries to come to grips with the darkness of the past, they find themselves face-to-face with the evil triggered so many years earlier