While tracking clues from a secret code penciled in the margins of mystery novels at a public library, Derek Knowles-Collier discovers a time capsule, an unpublished author and a gravestone that may finally put his haunting past to rest. At Queensview Elementary, grade-six students are required to complete a community service unit as part of their school curriculum, and Derek is assigned to repair duty at the local cemetery.

Derek is not happy about his assignment. When he was very young, his friend Dennis was killed by a car after running into the road to catch a ball. Ever since, Derek has had recurring nightmares, and he is afraid that spending time in a cemetery will make it even harder for him to sleep through the night. When it rains, the lessons take place in the nearby public library. One day, a book arrives at the library, an anonymous donation that happens every year. On reading the book, Derek and his group mates find a secret code written on an inside margin. One code leads to the next, with the last code leading the students to a time capsule. The book includes a secret code for readers to decipher!