Muna's fortunes changed for the better on the day that Mr and Mrs Songoli’s younger son failed to come home from school. Before then her bedroom was a dark windowless cellar, her activities confined to cooking and cleaning. She’d grown used to being maltreated by the Songoli family; to being a slave. She’s never been outside, doesn’t know how to read or write, and cannot speak English. At least that’s what the Songolis believe. But Muna is far cleverer – and her plans more terrifying – than the Songolis, or anyone else, can ever imagine ...