An expedition group led by Professor Shestakov arrives in one of the regions of Siberia to search for diamonds. The research begins with a dramatic event: The expedition leader dies suddenly. However, the geologists decide to continue the difficult, dangerous hike along the taiga "diamond trail".
| Actor | Role |
|---|---|
 Natalya VelichkoNadjeshda | Nadjeshda |
 Sergey PolezhaevProfessor Pavel Shestakov | Professor Pavel Shestakov |
 Nina IlyinaVera Lesun | Vera Lesun |
 Stasys PytronaitisFjodor | Fjodor |
 Sergei IvanovLyonka | Lyonka |
| BBuda VampilovDirigent Nikolay | Dirigent Nikolay |
 Paul DahlkeProfessor von Heyden | Professor von Heyden |
 Maksim MunzukNot listed | Not listed |
 Pauls ButkevicsDmitriy Borovskiy | Dmitriy Borovskiy |