A classic children's story by Swiss author, Johanna Spyri, published in 1880 and translated into English in 1884.
Orphaned Adelheid (Heidi) has been living with her Aunt Dete, up until the age of five. The book opens with Dete hauling the child up a mountain, because she has a job in Frankfurt, and can't take Heidi along. She plans to leave her in the care of her curmudgeonly grandather, a recluse who has lived in a cabin in the high Alps since the death of his son and daughter-in-law (Heidi's parents) in a fire.
Although he is reluctant to take her, at first, Heidi's happy and loving nature wins the old man over. As Heidi grows up, running wild on mountains with the goats, and without formal schooling, his coldness thaws a little and he begins to interact with people again, starting by helping his neighbours (the local goatherd, Peter, his widowed mother, and blind grandmother) who Heidi has befriended, and all of whom come to love her. Peter becomes her best friend.
Spyri paints an idyllic picture - the families on the mountain are materially poor, but are warm and loving people, surrounded by nature's beauty, and in the main, content. They aren't perfect - The Grandfather has a lot of repressed anger, and is gruff and harsh, Peter is selfish and greedy and so on, but overall, life is good
Then after three years Dete returns, and spirits Heidi away to a 'better life' as a companion to Clara, the crippled daughter of a rich man, Herr Sessemann, in Frankfurt. Heidi fails to adapt to the constrained life, frequently throwing the household into uproar with her thoughtless actions (such as adopting a litter of kittens). Whilst almost everyone in the household come to adore her, the housekeeper Fraulein Rottenmeier is appalled by her lack of education and uncivilised ways, and Heidi is increasingly homesick for the Alps. When she becomes sick and starts sleepwalking, Herr Sessemann decides to send her home, where she can be happy.
Apart from the friends she makes, Heidi takes one key thing back from Frankfurt - she has learned to read.
Happy, back on the Alp again, Heidi passes her learning on to Peter, over the winter, and the following summer Clara comes to visit her. Peter becomes jealous and resentful of the attention Heidi gives to the older girl, and in a fit of pique pushes Clara's wheelchair off the mountian, smashing it.
Forced by circmstance to try to overcome her disability, Clara learns to walk and Herr Sessemann rewards Peter with a penny a day forever - riches beyond his imaginings.
Shortly afterwards, Clara's doctor (and Heidi's friend) comes to visit, and persuades the Grandfather that despite being happy where she is, the girl needs a proper education. The Grandfather, therefore, decides to come down from his mountain during the winter, so that Heidi can attend school, completing his redemption and reintegrating him into his community.
It sounds corny, and perhaps it is, but the lively writing redeems the book, and Heidi is a far less irritating and saccharine heroine than, say Pollyanna, falling into scrapes, often with very funny results (her nighttime wanderings in Frankfurt convince the household that they are being haunted, for example), and she is an easy character for young girls to empathise with. It's old-fashioned, wholesome, and a really good read, if you can introduce children to it before TV and modern life makes them cynical. There's nothing wrong with a little innocent niceness, after all.
There are two sequels featuring Heidi - Heidi Grows Up and Heidi's Children, both written by Spyri's translator, Charles Tritten, which retain the style and essential innocence of the first book. As far as I know, nothing else by Johanna Spyri herself survives in print.