Elli is thirteen years old and she suffers from a heart disease. She will die soon but there is no donor heart in sight. But there is a new hope: the doctors want to transplant a pig heart with her DNA. It's her last chance. But she refuses. She is vegan and there is no way another living creature is going to die for her. Her mother, Maja, is willing to do literally anything to convince her to take the heart.

Heidi, is an eight-year-old Swiss orphan who is given by her aunt to her mountain-dwelling grandfather. She is then stolen back by her aunt from her grandfather to live in the wealthy Sesemann household in Frankfurt, Germany as a companion to Klara, a sheltered, disabled girl in a wheelchair. Heidi is unhappy but makes the best of the situation, always longing for her grandfather.

Nine-year-old Anuk Steffen plays the title role of the new Heidi film. Full of curiosity, she watches the film crew at work, and is especially intrigued by the sound engineer. Anuk takes us to a mysterious studio, where she becomes part of a fascinating experiment.