The book is about three adopted girls, Pauline, Petrova and Posy Fossil, sent by Matthew Brown, frequently referred to as Gum, to his great-niece, Sylvia and her childhood nanny.
Sylvia is outwardly annoyed at Matthew for all the children, though she is inwardly pleased. Nonetheless, by the time the second child is sent she is wary of the arrival of more children, and, as predicted, Matthew sends the third and final child, Posy, with her comes a pair of ballet shoes.
Gum, possibly fearing his great-niece's reaction to the filling of the house with children, leaves for an expedition with a friend, and leaves money behind to keep the household going for the next five years. However, when he does not return on the planned date, the money is used up, Sylvia and Nana, the nanny, are forced into taking inboarders:Mr. Simpson, who runs a repair garage; Doctors. Jakes and Smith, a pair of professors who take over the children's schooling after Sylvia can no longer afford their school fees, and Miss Theo Dane, a dance teacher, who arranges for the children to begin at the Children's Academy of Dancing and Stage Training.
As the book continues the children start to take on jobs in the Academy performing various plays, and putting money towards the household, the eldest Pauline, becomes a stage and screen actress. Petrova struggles with her duty to help support the household in the only way she is capable of, as a child, performing on stage, but is happiest when helping Mr. Simpson in his garage and dreams of flying a plane one day. Posy is developing into a brilliant ballet dancer, receiving private lessons from Madame Fidolia, the Academy's head.
The end of the book finds Pauline going to America to become a movie actress, Petrova is sad that she can do so little to help the family, and Posy, sometimes arrogant, is continuing her lessons with Madame Fidolia. Just as Pauline signs her contract Matthew Brown returns home. Though the end of the book leaves the children's future unclear, the general feeling is that they will have positive careers, even Petrova, whom Matthew promises to take flying.
A 1976 BBC adaptation won the BAFTA for Light Entertainment for producer John McRae in 1976 and in 1977 received an Emmy for Outstanding Children's Special. It stared Elizabeth Morgan as Pauline Fossil, Sarah Prince as Posy Fossil and Jane Slaughter as Petrova Fossil.
A 2007 BBC adaptation starred Emma Watson as Pauline Fossil, Yasmin Paige as Petrova Fossil and Lucy Boynton as Posy Fossil