 Fifteen strangers of various ages and backgrounds are brought together by a scientific experiment in Frankfurt, Germany. They are committed to live for twenty days in a state-of-the-art nuclear fallout shelter. During the first days, they live in harmony, in despite of the cultural differences, the stale food, and the lack of entertainment. But near the end of the experiment, these people find out that a real nuclear attack is in progress. While it is widespread panic outside of the shelter, things take a turn for the worst inside.