Professor Brian Cox visits some of the most stunning locations on earth to describe how the laws of nature have carved natural wonders across the solar system. Brian descends to the bottom of the Pacific in a submarine to witness the extraordinary life forms that survive in the cold, black waters. All life on Earth needs water so the search for aliens in the solar system has followed the search for water. Soaring above the dramatic Scablands of the United States, Brian discovers how the same landscape has been found on Mars. And it was all carved out in a geological heartbeat by a monumental flood. Armed with a gas mask, Brian enters a cave in Mexico where bacteria breathe toxic gas and leak concentrated acid. Yet relatives of these creatures could be surviving in newly-discovered caves on Mars.