Having lost her father at an early age, farm security guard Chan Sai-Mui grew to be an outspoken and determined woman who would do her utmost to protect her home village. It is her sincerity that has won her respect from all villagers of the Leung Choi County. One day, she mistakes the newly appointed agricultural magistrate Tse Wong-Sheung for a thief and the two of them have been bitter enemies ever since. After Sai-Mui saves Wong-Sheung from being framed for a crime, and they begin to spend more time together, Sai-Mui slowly falls in love with Wong-Sheung.

明朝洪武年间，良材县农官陈忠之女陈细妹 继承了亡父的遗志，从小便有锄强扶弱之心，义字当头，成为良材县人见人爱的女护农。大利米店老板谢苍天 为感激圣上御赐九龙白玉碗，而将其子取名为谢皇上 。谢皇上文采风流，自恃聪明绝顶，势要成为良材县为民请命的好官。谢苍天虽唯利是图，但为圆其子心愿，不惜重金捐官，让谢皇上当上了农官，还聘请了发誓不说话的师爷戴从文 和几名恶衙差给他。戴从文才高八斗，料事如神。在他的帮助下，谢皇上屡破奇案，两人惺惺相惜，合作默契，关系更为密切。此后，谢皇上接受戴从文的建议消解了与陈细妹的误会，并聘请她作为女护农。