Thirteen-year-old Ava Bonney is different. While her friends play, Ava searches for roadkill. She knows studying animal decomposition is an unusual hobby, but Ava doesn't care what other people think.

Then, one night, when Ava sneaks out to find a fox, she instead stumbles upon the body of Mickey Grant. Despite his many years in the police, Detective Seth Delahaye has never seen a murder case like this one - as though the victim was set upon by a wild animal. Nor has he met anyone quite like Ava: so determined, resourceful and unusual.

And when another boy goes missing, he has no idea that Ava will become his secret weapon in the hunt for a killer.