The Killing Jar by Nicola Monaghan

Kerrie-Ann lives with her drug addict mother in a housing estate in Nottingham, England. By 10, she's a drug courier for Uncle Frank, her mom's boyfriend. Basically motherless, Kerrie-Ann struggles to grow up in an awful environment while taking care of her younger brother. Her only real friend is Mark, another young runner, but drugs take their toll on both him and Kerrie-Ann. At times, she dreams of a different life. When she was young, she learned all about entomology from a neighbor and thinks about going to the Amazon. Will Kerrie-Ann be able to escape or be destroyed? While the subject matter of the novel is bleak, Kerrie-Ann is an interesting character and hard to forget.