An ear-shattering scream pierces the quiet Glasgow street as a mother stands frozen in her doorway, groceries strewn at her feet. Her son holds a bloodied knife while his father lies dead before him.

As Logan Martin begins his prison sentence for the brutal murder of his father, the eighteen-year-old’s aunt hires private investigator Teàrlach Paterson. She believes Logan is innocent and wants Teàrlach to uncover the truth.

Teàrlach’s visit to the Martin family home yields two disturbing discoveries: a pentagram etched under the carpet in Logan’s sister’s bedroom, and a link to the sinister deaths of their elderly neighbours—a journal with the same ominous symbol lies in the couple’s home.

While ritualistic murders plague the city, bodies placed precisely on an occult pentagram, bound in intricate knots, Teàrlach and his team unearth the sinister inspiration behind the killings in a mysterious ancient map.