Soviet specialists are building a hydroelectric power station in a Middle Eastern country. To continue the work, it is necessary to carry out an explosion... But no one even suspects that an old German ammunition depot is hidden nearby, underground. An accidental explosion would suit the British company that lost the order to the Russians. Weber, Greerson, and Gedda are faced with a problem: they need to warn the Russians about the danger. Each of them has had encounters with Soviet people in their lives...