Yuri Norstein and his wife Francheska Yarbusova have spent four decades working on a single animated film, "The Overcoat," adapted from Nikolai Gogol's story. The film follows the Russian couple in their studio as they describe the hand-cut, layered technique that makes their work so slow: each frame built and shot individually, with backgrounds and figures arranged by hand under the camera rather than drawn or computer-generated. Despite being far less famous internationally than Walt Disney or Hayao Miyazaki, Norstein is treated by animators and critics as one of the medium's greatest practitioners, and the film includes voices explaining why his earlier shorts, made with Yarbusova as designer, are considered landmarks of the form. The couple discusses the toll of the project, the perfectionism driving it, and why they have kept going despite the film remaining unfinished after forty years. It is a portrait of obsessive craft as much as a profile of two artists, built around the strange fact of a masterpiece still being made.