"The film, based on pre-Christian Finnish mythology and Sami shamanism, is set in Finnish Lapland and centers on a young woman, Pirita. In the snowy landscape, Pirita and reindeer herder Aslak meet and soon marry. Aslak must spend time away for work, leaving his new bride lonely. In an effort to alleviate her loneliness and ignite marital passion, Pirita visits the local shaman, who indeed helps her out; but in the process turns her into a shapeshifting, vampiric white reindeer. The villages' men are drawn to her and pursue her, with tragic results." via Wikipedia
This is the 1986 restoration (recorded off of Finnish television) which is a bit shorter than the original cut. When you watch this be sure to switch it to the SECOND audio track as the first is Russian and it interferes with the entire film.