Four young Muscovites - two boys and two girls - travel to the Altai for a rafting trip on a mountain river. Cut off from civilization, face to face with nature at its wildest our heroes are not able to relax but instead are forced to fight for survival. They ask the help of a group of apparent 'sportsmen-boaters' whom they encounter on the river. These agree, but then our heroes realize that they have been taken hostage by criminals.