The advent of the Wall Heidi's thirteenth birthday is coming up, but she's disappointed -- her mother is pregnant and refuses to make the annual summer visit to Heidi's grandmother. What's more, it's 1961 and the government is cracking down on border crossers, people who work in the West but live in the East. Heidi's father is a border crosser, and her best friend, Petra, has been forbidden to see Heidi until her father finds a new job in East Berlin...