When Sheryl Williams marries dashing soldier Alun Powell, she finds her happiness is shortlived.When Alun leaves the army he is unable to find work and, with their baby Caitlin, they are forced to live in the slums of Cardiff's Tiger Bay, where Alun becomes involved in a fight and is imprisoned. His parents reluctantly agree to look after Caitlin so Sheryl can find work, but one day seven-year-old Caitlin, without a word to anyone, goes off to find her mother. As night falls and the police search for the little girl, Sheryl fears she will never see her beloved daughter again.