Daphne Snowdrop Bluebell Riley "Arthur Lucan" gets fired from her job at the Black and White Laundry by manageress Miss Chester "Myrette Morven" for over-starching a man's shirt, shrinking a woman's combinations, and burning a hole in the vicar's chest protector. However, lawyer Clifton Hill "C Denier Warren" arrives to inform Mrs Riley that she has been left the laundry in a relative's will. And, when daughter Kitty "Kitty McShane" gets fired from her position at St Mildred's School for Young Ladies, Old Mother Riley mortgages the laundry to buy the school from headmistress Miss Carruthers "Enid Hewitt", outbidding potential buyer Lady Gertrude Meersham "Ethel Royal" by sixpence. However, the school's French mistress, Mlle Leblanc "Jenny Mathot", is in league with crooks who were planning to buy the school, because a railway branch line is proposed which will go right through it. They set fire to the school in order to buy it cheap.