Thomas Lewis returns to his family home to attend his father's funeral, pursued by 'voices' and 'incidents' that have tormented him all his life. His marriage ruined, his children estranged, his sanity precarious, he fears that someone - or something - wants him dead.
His young niece, Gemma Lewis, behaves suspiciously at the family gathering and he soon learns that she is both a natural telepath and telekinetic and reveals that she has been guided and protected by an 'angel'. Gemma forces him to embrace his gifts but as he does so, he is cursed by stigmata - an arcane phenomenon that sets both of them apart as freaks of nature and brings them to the attention of the sinister Department of Security and the cultists.
The physical and metaphysical opposites to the Lewises - the feared Sheppards - renew their old vendetta. The eldest, Paul Sheppard has his own 'angel' - a paranormal entity of many names: Ahriman, Ban-Sidhe, Ba'al, the First Satan - which possesses him, driving him to a final, fatal confrontation with Thomas Lewis and his extraordinary niece.