This is a beautifully written book about a five sisters who commit suicide. It has a unique style in that there is no real protagonist. Instead there are two groups of characters. The first are the Lisbon girls, whose far-away lives and deaths drive the book. Then are the teenage boys who admire and idolise them. Although the book is written from their point of view, the reader has insight into these boys only through their feelings and actions towards the girls.
This unfathomable nature of the characters is purposeful because the book is about the impossibility of understanding adolescence, both of others' and your own. The main characters struggle to understand the Lisbon girls as if revealing the truth about them would explain something in their own lives. The final act of suicide, which tears the girls out of their reach completely, is the most mysterious of all, and leaves them obsessed.
As the boys ponder about the suicides (years later when they are grown men), collect weird items that the girls left behind and speak to everyone who has interacted with them, you begin to put together a hazy and hopelessly incomplete image of the girls' lives. In the end, no one can explain the motivations behind the their actions, and the reader, like every character in the book, is left wondering.
I would recommend reading the book and watching the film - both equally enchanting.