The Marriage Certificate.

The wife of a prominent psychiatrist can't find her marriage certificate one day. This "jiehunzheng" is all important. Without it, the family officially has never existed, including the daughter. The couple go on a wild goose chase through the Chinese bureaucracy, meeting catch-22 all the way....they need a certificate to get a new one, etc. They even journey back to the People's Commune where they met, now the site of modern private enterprises where nobody even recalls the former occupants.