In pre-World War II London, Ernie Mott (Cary Grant), a Cockney layabout whose father was killed during World War I, learns that his mother, Ma (Miss Ethel Barrymore), is dying of cancer. In an effort to relieve his mother from the strain of running her shop on her own, Ernie pledges to help her with the business. Ma's failing health and financial desperation lead her to engage in some crooked business dealings, while Ernie courts trouble as he gets involved with a beguiling gangster's wife.