In 1991, eight people enter an artificially created and sealed biosphere called Biosphere 2 in Arizona. The purpose is to investigate whether it is possible to create a functioning ecological system where plants, animals and humans can live for two years. The biosphere contains rainforest, desert and even a coral reef, and the participants grow their own crops. At first it seems that the experiment is successful, but there are signs of division in the group and when oxygen levels suddenly start to fall, the threat becomes apparent. Documentary filmmaker Matt Wolf mixes film clips from the 90s with recent interviews with the participants to provide perspective on one of the most spectacular and acclaimed research projects in a closed ecosystem.