An uneducated youth, William Booth left home in 1849 at the age of 20 to preach the gospel for the New Methodist Connection. Six years later he founded a new religious movement which succeeded to such a degree that the Salvation Army (which it became) is now a worldwide operation with massive membership. In many ways Booth's story is also that of the Victorian poor, as he and his wife Catherine made it their lives' work to battle against the poverty and deprivation which were endemic in the mid- to late-1800s. Indeed, it was Catherine who, although a chronic invalid, inspired the Army's social policy and attitude to female authority. Her campaign against child prostitution resulted in the age of consent being raised and it was Catherine who, dying of cancer, encouraged William to clear the slums. Roy Hattersley's dual biography is not just the story of two fascinating lives but a portrait of this integral part of British history.