The film tells about the main events in the construction of the Baikal-Amur Mainline, which took place in 1975. A meeting of builders dedicated to the opening of the central section of the Baikal-Amur Mainline "BAM - Tynda", builders greet the first festively decorated train. Start of construction on the Davan pass of the Baikal ridge. Snow-covered houses of builders. Blasting work on the construction of the tunnel. Builders are chopping wood. A column of trucks is moving on the ice of Lake Baikal. The tractor is pulling the crane. Loading soil onto dump trucks. Tracklayers are working. Opening of the bridge over the Amur River. Builders in the dining room, in the trailers. A kindergarten in one of the villages. Builders listen to a radio broadcast dedicated to the workers of the Baikal-Amur Mainline. Landscapes of Transbaikalia. Forests, mountains, meadow - places where the highway will pass. Types of Lake Baikal. Evenk village. Evenk houses. Folk holiday in the village. Evenk talks about the problems associated with the construction of the road (synchronously). The first press conference of the Deputy Minister of Transport Construction, Head of the Glavbamstroy KV Mokhortov (synchronously). The film includes interviews with the manager of the construction of the Baikal section of the highway V.M. Krivochuprin, builders and local residents (synchronously). Types of Severobaikalsk, Nizhneangarsk. Construction of houses in the village.