Lego's Bionicle line has sprouted this complicated but impressive family movie, Bionicle: Mask of Light, to bolster the toys' mythic appeal. The story focuses on the robotic Matoran tribe from the island of Mata Nui, which is protected by six powerful guardians known as the Toa. Two small Matorans--one a potentially heroic "herald" and the other a historian-witness called "chronicler"--find a sacred mask of light, suggesting the imminent of arrival of a seventh Toa. Identifying that mystery figure proves difficult, however, especially with the evil spirit of shadows, Makuta, attacking Matorans with mechanized-crayfish warriors in a bid to possess the precious mask. This is the kind of out-of-nowhere, dense fantasy that requires one to get up to speed quickly on a lot of exotic detail, terms, history, etc. But Mask of Light is also enjoyable as expressive, CGI animation with thoughtful art design, striking color, and excellent vocal performances.