whodunnit

noun

1. （在结尾时才能知道谁是谋杀犯的）侦探小说，侦探戏剧
   a story, play, etc. about a murder in which you do not know who did the murder until the end

1. 凶杀悬疑小说（或电影、戏剧）
   A whodunnit is a novel, film, or play which is about a murder and which does not tell you who the murderer is until the end.