Shy, fat Hannah Smith has a popular, thin twin sister, a slender mother obsessed with cleaning, and a fat father in prison for violating federal laws against distributing junk food.

The U.S. government controls access to chocolate and other foods considered fattening. Parents of fat youth must pay a special tax or their children must go to a Laboratory School for the Weight Challenged -- A.K.A. "Fat School" -- where they are forced -- and shamed -- to lose weight.

As her father's parole hearing nears, Hannah wants desperately to find out who turned her father in to the police. She enlists her best friend and secret crush, Christian, in her investigation. But with Hannah's father's businesses faltering, her mother can no longer pay her Fat Tax, and Hannah is sent to Fat School. She continues to search for her father's betrayer, but soon finds herself drawn into a more frightening mystery: the largest teenagers at Fat School are disappearing.

How far will Hannah go to find the truth?