Wither - Lauren DeStefano

What if you knew exactly when you'd die? The first book of The Chemical Garden Trilogy.
By age sixteen, Rhine Ellery has four years left to live. A botched effort to create a perfect race has left all males born with a lifespan of 25 years, and females a lifespan of 20 years--leaving the world in a state of panic. Geneticists seek a miracle antidote to restore the human race, desperate orphans crowd the population, crime and poverty have skyrocketed, and young girls are being kidnapped and sold as polygamous brides to bear more children.
When Rhine is sold as a bride, she vows to do all she can to escape. Yet her husband, Linden, is hopelessly in love with her, and Rhine can't bring herself to hate him as much as she'd like to. He opens her to a magical world of wealth and illusion she never thought existed, and it almost makes it possible to ignore the clock ticking away her short life. But Rhine quickly learns that not everything in her new husband's strange world is what it seems. Her father-in-law, an eccentric doctor bent on finding the antidote, is hoarding corpses in the basement; her fellow sister wives are to be trusted one day and feared the next; and Rhine has no way to communicate to her twin brother that she is safe and alive.
Together with one of Linden's servants, Gabriel, Rhine attempts to escape just before her seventeenth birthday. But in a world that continues to spiral into anarchy, is there any hope for freedom?