Heidi's Children is a 1939 novel, the second of four sequel novels to Johanna Spyri's original Heidi series, written by Spyri's French and English translator, Charles Tritten. It was originally published in French by Flammarion in Paris in 1939, and in New York by Grosset & Dunlap in 1939.
It was preceded by Heidi Grows Up: A Sequel to Heidi.
One spring, the flowers budding in Dorfli inspire Eileen to suggest Heidi have the former's little sister, Martha, visit the village as their guest. After bickering, Martha is eventually taken to Heidi's, but she does so grudgingly and complains a great deal. Eventually, though, Heidi's grandfather eventually teaches the girl a prayer, the verses of which uplift her. Wanting to join in family traditions, Martha is taken to pick berries with her friends. One of her companions gets stuck under a cliff. Martha climbs down to rescue her. They both fall to the ground, but survive, and eventually come home.
Heidi has been pregnant most of the book. Eventually, she gives birth to twins, whom the grandfather names. Soon afterwards, the grandfather goes quieter and stiller, and eventually he dies of old age. The family, with Martha, moves (back) up to the mountain home where, among other things, the building shed is turned into a cheese factory. Martha and Tobi, her brother, take the goat herding job.
One day, Heidi takes Martha to the "enchanted garden," but when the sun's down, Peter frantically announces that Tobi's gone. Everyone frantically searches for him to no avail. Martha searches on her own, despite her parents' protests, and after some dangerous adventures through the mountain sides, she finds herself in the grazing meadow. Under the Rainy Day Rock, she accidentally finds the sleeping Tobi and after his stubborn resistance and her desperate name shouts, she realizes the shouts for her grandmother came from herself, and takes Tobi back down, safely, to the mountain home.