The hero of the film is an ordinary driver of a Moscow taxi, a kind and decent man. Each new working day promises him new meetings, acquaintances — sometimes joyful and pleasant, and sometimes demanding from him severe determination and courage.

While doing their work on the deep underwater station two aquanauts discover strange mystery: it seems as if one of the aquanaut's girlfriend who recently died in a car crash had turned into a big manta fish. That manta writes words on the station's port-holes and tries to draw attention many other ways.