This timeless rags to riches story concerns the vacillating fortunes of the Dorrit family. The kind-hearted Amy (Claire Foy), the Little Dorrit of the title, looks after her proud father, William (Tom Courtenay - The Golden Compass) who is a long-term inmate of Marshalsea debtors' prison in London.
But their fate is transformed by the unexpected arrival from overseas of the benevolent Arthur Clennam (Matthew Macfadyen - Spooks), who is determined to solve the mystery of his father's dying words, "Put it right, Arthur." He is sure this phrase is in some way connected to the Dorrits' plight and sets about rectifying the situation - discovering they are sitting on a huge fortune, a fact which thrusts the family into the upper echelons of society.
As the Dorrits meet a variety of characters from rich to poor, a deep bond grows between Arthur and Amy, and a dark villain Rigaud (Andy Serkis) threatens to spill a long-held family secret.