Sam Pargeter and his younger brother and sister have always been poor, but they lead a happy life in the country with Ma and Pa. But when Pa goes off to America to seek his fortune, things go terribly wrong. The children find themselves whisked off to live with Aunt Maud and miserable Uncle Bert in the most dangerous part of London, called Devil's Acre, and put to work, just like Oliver Twist in their favorite book. When life in the city proves impossible, the three children decide to leave. Together with their small dog, Patch, they set out on a hazardous journey to find their long-lost grandfather.