It's 1979, and thirteen-year-old Lydia has no idea how she'll cope when her dad announces that the family has to sell up and move onto a Thames sailing barge in Essex. With his girlfriend. And her three kids. Between trying to keep her clothes dry in a leaky cabin, disastrous hair-dye attempts, awkward encounters with local boys, and coping with her suddenly enormous and troublesome family, Lydia fears she'll sink rather than swim. At turns heartbreaking and uplifting, through Lydia's innocent and perceptive voice we find out that while the mud may stick, the tide can turn - and in unexpected and joyful ways.