Lauren Oliver's Delirium follows the months before Lean is scheduled to be cured of deleria, the disease of love.  Everyone goes through it, and society is seemingly peaceful and calm as a result.  No falling in love means no insanity, no wars, no troublesome partner squabbles.  At eighteen, everyone is surgically operated on to remove the part of their brain that can love and matched with a suitable heterosexual partner for life.  And assigned a number of children to have. 

But sometimes it goes wrong, as it did with Lena's mother, on whom the operation was not successful.  Despite four tries, they never did cure her of love.  As a result, Lena grew up first in a household full of love and games, and then, after her mother was said to have committed suicide, in her aunt's cold household, their whole family shamed by the blemish of her mother's failure.

Very slowly (sometimes a bit too slowly for the pace of the story) Lena begins to understand that the world of safety constructed around her is built on a backbone of violence and deception.  She realizes it when she meets Alex, who has the scars of the cure behind his ear, but in fact grew up outside Portland as an Invalid in the Wilds.  And he hasn't been cured at all, and they fall in love.  And she realizes it when she sees her best friend Hana change, suddenly and dramatically, into someone who goes to secret music concerts.

Finally, it all breaks apart when (SPOILER!!) Alex shows her that her own mother was alive this whole time, kept in the endless prison of the Crypts, carving the word "love" over and over into her cell.  And then Lena knows:  she has to leave.  All the safety of her society comes to seem like a cage, and she'll do anything to get out.  Unfortunately, as she and Alex are planning their escape, things get very difficult and it's ultimately impossible to have a grand happy ending.  But the ending is happy in smaller ways.  Lena will survive, intact, and keep her ability to love.

Favorite quotes:

"You may think the past has something to tell you.  You may think that you should listen, should strain to make out its whispers, should bend over backward, stoop down low to hear its voice breathed up from the ground, from the dead places. [...] But I know the truth:  [...] I know the past will drag you backward and down, have you snatching at whispers of wind adn the gibberish of trees rubbing together, trying to decipher some code, trying to piece together what was broken.  It's hopelss,  The past is nothing but a weight.  It will build inside of you like a stone."   (p. 176)

"One of the strangest things about life is that it will chug on, blind and oblivious, even as your private world--your little carved-out sphere--is twisting and morphing, even breaking apart.  One day you have parents; the next day you're an orphan.  One day you have a place and a path.  The next day you're lost in a wilderness.
     And still the sun rises and clouds mass and drift and people shop for groceries and toilets flush and blinds go up and down.  That's when you realize that most of it--life, the relentless mechanism of existing--isn't about you.  It doesn't include you at all.  It will thrust onward even after you've jumped the edge.  Even after you're dead."  (p. 303)