The Soviet cargo ship "Nezhin" in a foreign port, somewhere in the Philippines, receives a large load of opium for the pharmaceutical industry and goes to Vladivostok. On the way, the crew catches a man named Saleh in the sea, who says that he escaped from a cargo ship on which a load of cotton caught fire. Soon, "Nezhin" finds an unknown abandoned "Mercury" ship and captain Ivan Ilyich sends a group of sailors there. Meanwhile, Saleh sneaks into the radio room and, mortally wounding the radio operator, incapacitates the radio station.