The Cloud Mystery is a scientific detective story. It tells how a Danish scientist, Henrik Svensmark, through pioneering experiments in a basement in Copenhagen, solved the mystery of how supernova explosions in our Galaxy and variations in the Sun govern climate changes on the Earth. Henrik Svensmark has discovered a new kind of aerial chemistry - triggered off by events in our galaxy - that determine the magnitude of clouds in our atmosphere. His discovery introduces a paradigm shift in meteorology. Now we have to re-evaluate the causes of global warming. A film crew has for 10 years documented how Henrik Svensmark struggles the to find the physical evidence of a celestial climate driver. The film demonstrates that science can be a rough place to be if you are in opposition to the established 'truth.' The Cloud Mystery is aimed at a wide audience. Astonishing pictures from our Galaxy, the Sun and cloud formations are mixed with spectacular animations to simplify the science. Comments by astronomers, geologists and climate experts will convey their sense of adventure, and give scientific weight to the discoveries presented. Lars Oxfeldt Mortensen has produced and directed a number of international acclaimed documentaries. He is the winner of numerous awards including CirCom Regional, Monte Carlo and Télé Science.