The movie is set during the Warring States Period. It tells the story of assassination attempts on the king of Qin by legendary warriors. Though the king is not named during the film, he does express his dreams of unifying China and the assassins consider him likely to fulfil them. So he is probably King Ying Zheng (lived 259 -210 BC, reigned 246 - 210 BC). In 221 BC he did manage to unify China under his command and became its first Emperor (Qin Shi Huang Di).
The film was Zhang's first attempt on this genre. Segments of the different versions of the story were told by different characters. Each segment used a different bright color theme, depending on the narrator. The different versions of a story remind the audience of Rashomon. The color theme changes remind the audience of the Matrix. The bright color themes remind the audience of many other Zhang Yimou's movies.
The film is rather moody, reflecting the thoughts of its six main characters who come to realize that the fate of China depends on their own decisions and actions. This feeling of responsibilitie seems to come in conflict with their personal desires, emotions and relationships to each other. This gives the film a sense of drama and somewhat approaches the sense of a classic tragedy.