Since she was orphaned, Sue Trinder (Sally Hawkins) has been brought up amongst pickpockets and charlatans. She has been protected and cared for by Mrs Sucksby (Imelda Staunton) who believes Sue is too good a girl to get directly involved in such a world. But when Mrs Sucksby's old friend Richard Rivers (Rupert Evans) offers 20-year-old Sue £3,000 to assist him in one of his scams, Mrs Sucksby cannot resist. Passing himself off as a proper gent, Rivers has befriended a young lady, Maud Lilly (Elaine Cassidy), who stands to inherit a fortune when she marries. However, Maud's maid has recently left her service and, without a chaperone, Rivers' access to Maud is limited. He wants Sue to be accepted as the new maid and to help him win Maud over. Once married, Rivers plans to have Maud committed to an asylum and he will then take her fortune for himself. Arriving at Briar, the estate where Maud lives with her wealthy bookish Uncle Lilly (Charles Dance), Sue enters another world.