Watch Heidi for Free: How to Stream the Movie Online at 123Movies. . Based on the ever-popular children's' novel by Johanna Spyri, "Heidi" follows the adventures of an indomitable young girl, forced to move to her grandfather's hovel high up in the Swiss Alps, where she she surprises all by settling in to a firm friendship, not only with her somewhat grouchy relative, but also with a new friend Peter, the goat-herder.