One of the central questions in this tale is culpability.
"What's the difference between what you want to believe and what you do?...And what's the difference between what you think and what you end up doing," Madeleine wonders.
She's a kid surrounded by adults--her parents, Mr. Grierson, the Gardners who shirk their duties and blame others for mistakes they make.The worst offender is probably Patra who blames illogically blames Madeleine for the death of her four-year-old.
Then there's Mr. Grierson, her teacher, who is guilty of possessing child pornography but not guilty of what police charge him with. Madeleine tracks him to Florida after he gets out of prison. She writes letters to him reminding him that he used to call her "Miss Originality," yet he seems to have forgotten her.
Madeleine is expert at hiking and traversing the streams and rivers in her canoe. She is less expert at deciphering social cues or understanding human relationships. Perhaps that is why she is fascinated by Patra and Leo's strange relationship.
However capable she is at wilderness survival, Madeleine is strangely powerless when faced with Leo's religious obsession or Lily's duplicity.