In the fog-choked alleys and gaslit drawing-rooms of Victorian London, a city oblivious to the terrors stirring beneath its cobblestones, folklorist Arthur Ashworth receives an unsettling bequest: Ashworth House, his ancestral home, a place steeped in shadows and whispered family curses. His inheritance soon reveals a horrifying truth – the house is a Nexus Point, a place where the Tenebrous Veil separating reality from an Otherworld of ancient, malevolent entities is perilously thin. From beyond this fragile barrier looms the Bone Collector, a cosmic horror of unimaginable hunger.

As manifestations of this encroaching darkness escalate – spectral Shade Hounds hunting through the night and ethereal Weeping Widows feeding on the city's despair – Arthur is thrust into a desperate investigation. He uncovers the existence of the Umbral Covenant, a clandestine society of London's elite, led by the brilliant and ruthless Lord Julian Thorne. Thorne, obsessed with forbidden knowledge and occult power, plans to exploit the upcoming Noctis Major, a rare astrological alignment, to perform a Grand Ritual. His aim: to tear open the Veil fully and merge with the Bone Collector, becoming its avatar and plunging London into an age of illuminated darkness.

Haunted by his own family's legacy of madness – the 'Ashworth Sight' that makes him acutely sensitive to the Veil's horrors – Arthur finds an unlikely ally in the courageous journalist Eleanor Vance. Together, guided by the fragmented lore of the long-lost Lamplighters and the desperate warnings in his ancestors' journals, they race against time. Arthur must locate and understand the Heart Sigil, a True Ward hidden deep within Ashworth House, his only hope of countering Thorne's apocalyptic designs.

But the price of activating such ancient power may be Arthur's own sanity, or his very soul. As the Noctis Major dawns, and London trembles on the precipice of an unholy transformation, Arthur must confront not only the human depravity of the Covenant and the cosmic dread of the Bone Collector, but the terrifying potential within his own blood. Will his desperate gambit save the city from being consumed by the Veil of the Bone Collector, or will he merely become another sacrifice to the endless, unknowable horrors that lie beyond?