Only half the title is true
OK I read this book and it clearly does tell you WHO the hijackers were. Well 4 of them mainly as it focuses pretty much entirely on the pilots. And it details their movements and training etc. But it is not very heavy on the WHY as the books sub-title says. Unless we assume that their desire to become "martyrs" was their sole motivation. The book is divided into chapters based on their youth, college and then breaks down their movements and activities based on the final year, final month, final week, final day etc. The closer it gets to 9/11 the shorter the chapters become and the final night and day are just a few pages.