The life of a chimney sweep in Victorian London is a harsh one. Young children are "apprenticed" to master sweeps and climb through narrow, twisting chimneys on a daily basis. They are abused and neglected and forced to work until they die or get to old to fit in the chimneys. Nan Sparrow is one such sweep. She has been indentured to cruel master Wilkie Crudd ever since she was abandoned by The Sweep, her protector and mentor. The only thing The Sweep left her was a piece of char that always stayed warm. Nan is getting older and worried about when she will no longer be able to work as a sweep. Then the day comes when she gets stuck and must call for help. Of course it is cruel Roger, who is jealous of her, who comes to save the day. He gives her the nudge to astonishing results. 

Nan wakes to find that she has not been burned alive, but has somehow survived. She also realizes that her char has saved her. The char has come alive and continues to grow and learn. Now named Charlie, they live together in hiding while the world believes Nan to be dead. Only mudlark Toby discovers her secret. But nothing can stay a secret forever. 

This was a moving tribute to friendship and sacrifice. We truly do save ourselves by saving others.