Every day, the world over, large amounts of high level radioactive waste are placed in interim storages which are vulnerable to natural or manmade disasters. In Finland the world's first permanent storage is being constructed — a huge system of underground tunnels hewn out of solid rock. It is essential that it lasts 100.000 years, as this is how long the waste remains hazardous. When the waste has been deposited, the facility will be sealed off, never to be reopened. But can we ensure that? How is it possible to warn our descendants of the waste we left behind? How can we prevent them from thinking they have found the pyramids of our time, mystical burial grounds, hidden treasures? Which languages and signs will they understand, and if they understand, will they respect our instructions?