Häkkinen, Sons of Night

Sons of Night is a mystery novel for children (over the age of nine). It's the beginning of summer vacation. A small town of Fort Sara is sleeping peacefully. Three schoolboys, Toby, Matty and Marc, are feeling bored and looking for something to do. Then, a mysterious van appears in town and strange events start to unfold. Soon the boys find themselves in the middle of a dangerous game. What is going to happen when the darkest hour of the night comes?