“400 Days” is a gripping and suspenseful thriller novel by renowned author Mark Green. The story unfolds over the course of 400 days, during which the protagonist, Jake Denton, faces a series of escalating challenges that push the boundaries of his endurance. Green weaves a tale of psychological tension, mystery, and survival as Jake navigates through a world that becomes increasingly hostile and unpredictable. The novel’s strength lies in its ability to keep readers on the edge of their seats, as they accompany Jake on a relentless journey that forces him to confront not only external threats but also the demons within.