Po Chu is always in bad luck, so she believes in Murphy's Law. One day a customer leaves a hundred thousand dollars, and she hides the money. By that time, the killer whom she hires to kill her boyfriend (who is also her boss) arrives. The customer also returns. Po Chu succeeds in keeping the money, but then she finds herself in trouble.
寶珠經常遇上倒楣事，深信「莫非定律」。她是餐廳侍應生，男友兼上司是有婦之夫，喜歡拈花惹草。有一天，客人的公文袋遺留在餐桌上，內有十萬元現鈔。寶珠據為己有，把款項放在馬桶的水箱內。殺手突然出現，原來她曾往殺手公司，想買凶殺死男友。客人返回餐廳，遍尋不獲，竟聲稱打劫。男友發現鈔票，與寶珠一輪爭奪。她雖成功，但大禍臨頭……
