One Big Happy Family is a thriller novel by author Jamie Day, published by St. Martin's Press on July 16, 2024. The hardcover edition runs 360 pages and carries ISBN 9781250283207.

The story centers on The Precipice, a legendary family-owned hotel perched on the rocky coast of Maine. When their father dies, three sisters — Iris, Vicki, and Faith — return to claim their inheritance just as a hurricane bears down on the coast. Old secrets resurface, loyalties fracture, and before the storm passes, murder comes to the hotel. Nineteen-year-old chambermaid Charley Kelley, caught up in the Bishop family's dark drama, must navigate her own hidden troubles amid the chaos.

Praised for its razor-sharp wit and Agatha Christie-style locked-room atmosphere, One Big Happy Family blends summertime suspense with family drama and unexpected twists. It has earned over 12,000 ratings on Goodreads with an average of 3.52 stars. An audiobook edition narrated by Saskia Maarleveld is also available.