Beneath the cobbled streets of Edinburgh, in catacombs carved from an ancient volcano, something hungry waits—and this year's sacrifice has a father who will stop at nothing to save her.

Walker Kane came to Edinburgh to rebuild his relationship with his daughter, Emily. A decorated search and rescue specialist haunted by years of dangerous missions, Walker hoped to find redemption in her smile, to make up for the years he'd missed while serving in the military.

But on the night of Emily's triumphant performance in The Tempest, Walker discovers she's been chosen as the next victim of an ancient ritual. A secret society known as the Cabal has orchestrated human sacrifices for over a thousand years, feeding a monstrous creature called the Grendsluagh that dwells in the volcanic catacombs beneath the city.

When Emily vanishes during Edinburgh's bustling summer festival, Walker must confront his worst nightmare—not enemy combatants on foreign soil, but a labyrinth of tunnels beneath his feet where an ancient evil has claimed countless victims. The creature has waited all year for its offering, and the Cabal's most powerful members will do anything to ensure the ritual is completed.

Laurel, a university librarian who stumbled upon the Cabal's secrets, races to help Walker navigate the forbidden depths. Max, an urban explorer mapping the catacombs while haunted by her friend's death in the tunnels, holds the key to finding Emily before time runs out. Together, this unlikely team must descend into darkness where symbols of power mark the creature's domain and every shadow might conceal razor-sharp claws.

But the Grendsluagh is not just a legend—it's very real, very hungry, and it's already tasted Emily's scent.

As the clock ticks toward dawn and the completion of the sacrifice, Walker must use every skill he's learned from years of impossible rescues. The tunnels are treacherous, the creature is ancient and cunning, and the Cabal will kill to protect their monstrous accord.

Walker's greatest mission isn't in some distant war zone—it's beneath the city streets, where the price of failure is his daughter's life.

Perfect for Readers Who Love:

• Jeff Long's The Descent (creatures in underground labyrinths)
• Paul Tremblay's horror novels (atmospheric, psychological dread)
• James Rollins' Sigma Force series (action with archaeological/historical elements)
• Jeremy Bates' horror thrillers (confined spaces, creature horror)
• Stephen King's monster fiction (ancient evil, small-town conspiracies)
• Search and rescue/ex-military protagonists with personal stakes
• Edinburgh's dark history and underground city tours
• Celtic mythology reimagined (Beowulf's Grendel meets modern horror)
• Father-daughter relationships tested by extreme circumstances
• Fathers who will sacrifice everything for their daughter — films like Taken with Liam Neeson
• Secret societies with ancient, sinister purposes

Story Details:

• Genre: Horror Thriller, Creature Horror, Action Thriller
• Setting: Edinburgh, Scotland (during festival season) + volcanic catacombs beneath the city
• Length: Short novel (approximately 50,000 words)
• Reading time: 4-5 hours
• Mood: Tense, fast-paced, claustrophobic, atmospheric, heart-pounding
• Themes: Redemption, sacrifice, ancient evil, father-daughter bonds, urban exploration
• Content note: Contains horror violence, creature attacks, peril to main characters, human sacrifice rituals (not graphic), underground/confined space scenarios

About the Book: Catacomb combines the visceral creature horror of The Descent with the fast-paced rescue mission urgency of military thrillers. Set against the backdrop of Edinburgh's real underground vaults and volcanic geology, this standalone horror thriller explores what happens when ancient evil collides with modern desperation, and when a father's love must face the unimaginable.

A standalone horror thriller from New York Times and USA Today bestselling author J.F. Penn.