The book's a first-person narration, but what's unique is that there are three first-person narrators. The story really belongs to Oskar, and he gives us a nonstop, mile-a-minute tour of his thoughts about everything. His grandparents have their own, quieter stories, that weave in and out of the narrative and are told as letters written to Oskar (by his grandmother) and to Oskar's father (by Oskar's grandfather). The stories are largely unrelated to Oskar's narrative, until they all catch up to each other at the end. They mirror the trauma Oskar's going through as they describe horrors from a different time but with the same consequences.