"Mediator #4: Darkest Hour" by Meg Cabot is a young adult fiction novel published by HarperCollins in 2004. This trade paperback book, part of the Mediator Ser., features 336 pages and is written in English. The story combines elements of romance, paranormal, and mystery, making it a thrilling read for young adults. With themes of monsters, ghost stories, and suspense, this book is sure to captivate readers with its intriguing plot and engaging storytelling.