prequel

剑桥词典

a film , book , or play that develops the story of an earlier film , etc. by telling you what happened before the events in the first film , etc.
（据已问世文艺作品的情节凭想象上溯创作的）先行篇，上篇，前传
Jean Rhys's novel "Wide Sargasso Sea" is a prequel to Charlotte Bronte's "Jane Eyre". 琼•里斯的小说《藻海无边》是夏洛蒂•勃朗特的《简•爱》的前篇。
比较
sequel 返回 prequel