Mary Poppins Comes Back (Paperback)
The books center on the magical English nanny Mary Poppins, who is blown by the East wind to Number 17 Cherry Tree Lane, London, and into the Banks' household to care for their children. Encounters with pavement-painters and shopkeepers, and various adventures ensue, until Mary Poppins abruptly leaves, i.e., "pops out". Only the first three of the eight books feature Mary Poppins arriving and leaving.
In Mary Poppins Comes Back, published 1935, nothing has been right since Mary Poppins left Number Seventeen Cherry Tree Lane. One day, when Mrs. Banks sends the children out to the park, Michael flies his kite up into the clouds. Everyone is surprised, when Michael reels his kite in, Mary Poppins is at the end of the string. She takes charge of the children once again (though she'll only stay "'till the chain of her locket breaks"). This time, Jane and Michael meet the fearsome Miss Andrew, experience an upside-down tea party, and visit a circus in the sky.
In the chapter "The New One" a girl, Annabel, is born into the Banks family, and concludes the family of now five children; three daughters and two sons. As in Mary Poppins, Mary leaves at the end (via an enchanted merry-go-round, throwing her locket towards the children as she disappears), but this time with a "return ticket, just in case" she needs to return.