A mysterious anomaly occurs off the coast of Cuba - a huge water tornado draws in water, draining the ocean. By the decision of the Soviet command, Belka and Strelka are sent to the island of fraternal peoples with an intelligence mission. Colorful Cuba, the azure expanse of the ocean and the underwater world shrouded in secrets meet the heroes. Four-legged researchers and their team face dangerous adventures that will not only lead them to unravel the Cuban anomaly, but also test their friendship for strength.