丽萍和小萍的父亲是鼎鼎大名的神偷,因一次失手而成了阶下囚.从此姊妹两生活拮据,丽萍只好步父亲后尘,以偷窃维生.某日,大贼唐标发现她手法高明,便将她的偷窃过程拍摄下来,要胁她跟自己合作.某日丽萍被一群飞型青年围困,私家侦探李子奇见状上前救助,两人一见钟情.不久标知道富家女黄文兰要在家中展览稀世珍宝,便要求丽萍偷取展览会的保安计划,丽萍逼得依计行事.事成后她才发现子奇是该展览会的保安负责人,为免连累他,她决定先行将珠宝偷去.展览夜,当标等人与丽萍争夺珠宝之际,小萍突然出现,并于无意中夺得珠宝.此时保安人员来到,将众贼一网成擒.子奇知道丽萍有偷窃行为,但亦谅解她的苦衷,决定不究既往,两人如前相好。

As the Cantonese 'Jane' Bond films evolved, the genre became less Bond-like, cutting down on the staging of fights and the flaunting of secret weapons. The heroine(s) remained an action figure, complete with quick wits and agile prowess, but the stories increasingly took on the jewel theft plot and the twilight world of decadent deviance. The Mysterious Sisters is no exception as director Ng Wui renders high class thefts in the style of the classic French film Rififi, and long stretches of action that unfold without dialogue.