马丁（伊利亚•伍德 Elijah Wood 饰）为了追寻偶像逻辑数学家亚瑟（约翰•赫特 John Hurt 饰）的足迹，来到牛津大学深造。他发现，寄宿的房东伊格莱顿太太（安娜•玛西 Anna Massey 饰）仿佛跟亚瑟交往甚密，而她的养女贝丝（朱丽•考克斯 Julie Cox 饰）却总是故弄玄虚。后来，马丁结识了壁球伙伴洛娜（蕾欧诺•瓦特林 Leonor Watling 饰），两人堕入爱河…… 　　亚瑟演讲时，马丁作为唯一的提问者，引起了他的注意。后来，二人在房东家不期而遇，发现伊格莱顿太太被人谋杀。现场唯一的线索是一个圆圈。二人被警方带走协助调查。此后又有一些人离奇地死去，而且他们的死因似乎还暗含着某个数学定律……Martin, a PhD student in mathematics, enrolls at Oxford in the hope of meeting his mentor, Professor Seldom. The young man manages to find lodging at Mrs. Eagleton's but in this house a stifling atmosphere prevails due to the landlady's attitude. Indeed Mrs. Eagleton, who happens to be a friend of Seldom's, is a haughty and unsympathetic woman who also stifles her daughter Beth. At the university, things do not fare much better as Martin is put in his place by his idol during one of Seldom's lectures. But his private life changes for the best as he starts an affair with Lorna, a beautiful girl he met during a game of squash. One night Seldom and Martin who find themselves at Mrs. Eagletons's discover her dead body. They are interrogated by the police. Soon afterwards they decide to lead their own private investigation...