SetinVictorian-eraLondonof1887,HettyandherfosterbrotherGideonareforcedtoreturntothefoundlinghospitalwhereshewasabandonedbyhermotherasababy.Hettyandherfriendshatetheiron-fistregimeofMatronBottomlyandgangleaderSheila.Hettyyearnstoescapeandgoinsearchofhermother.