Cast:
Sergei Stoliarov (Vorontsov)
Igor Vladimirov (Skvoreshnya)
Sergei Golovanov (Gorelov)
Pyotr Sobolevski (Druzhinin)
Vakhtang Ninua (Lortkipanidze)
Sergei Komarov (Professor)
Antonina Maqsimova (Bystrykh)
Leonid Pirogov (Bystrykh)
T. Dobrotvorski (Bazov)
Pavel Luspekaev (Kartsev)
Mikheil Gluzski (Ivashev)
Irina Preisi (Sidorina)
Igor Bristoli (Pavlik)
Daniel Slavin
Mikheil Mineev
Petre Morskoi
Irine Magalashvili
Karaman (Guguli) Mgeladze
Igor Balla (Mikhail)

Soviet ship "Arctic" sinks in the Atlantic. Another ship, French "Victoria" sinks in the Pacific. An expedition from Leningrad on board of the "Pioneer" submarine tries to find out what happened with the ships but a mole on board of the submarine does his best to interfere.