the Children of Lost: Book One Lost Mystery Trilogy (Hardy Boys Undercover Brothers Series #34)

The boys go on a chilling mission—camping in the woods where children have suddenly begun to disappear. Every time a child disappears, the word "LOST" has appeared outside their tent…and they are never heard from again. The boys think they’ve got things covered; they’re ATAC agents after all. But when an "L" appears outside their tent their first night in the woods, things take a turn for the creepy.