Maiden's Vow is revolves around a restaurant that is closely intertwined with the stories of four women of different generations. It portrays the commonest marital problems and various kinds of stress suffered by women over the centuries.
In the late Qing Dynasty – Ngai Yu-Fung (Sheh Charmaine)'s family goes into a decline and, without a choice, she is married off to Wong Yuk-Lun (Chan Kin Fung) who later ends up losing all his money. Fung sells the love token given by her first lover Yu Tsz (Ma Tak Chung) in exchange for money, with which she sets up the Phoenix Restaurant.
During the May Fourth Movement – Fung's daughter Wong Chi-Kwan (also played by Sheh Charmaine) elopes to Tianjin with her teacher Lee Kat-Cheung (also played by Ma Tak Chung). The pair finally split up, following which Kwan moves back to Beijing and the Phoenix Restaurant is already dying on its feet.
In the late 1960s – Fung's granddaughter Pak Wai-Chun (also played by Sheh Charmaine) goes out to work without letting her husband Tai Lap-Yan (also played by Ma Tak Chung) know about it. Yan takes revenge by cheating on Chun and their marriage finally collapses. Subsequent to their separation, the ex-couple are put in charge of the promotion of the Phoenix Restaurant.
At the start of the 21st Century – Fung's great-granddaughter Tai Sze-Ka (also played by Sheh Charmaine) and her boyfriend Fong Ka-On (also played by Ma Tak Chung) are too egocentric to maintain a cohabiting relationship. Having recovered from the break-up, Ka is resolved to bring the family’s century-old business to its heyday. With the "Phoenix Recipes" handed down from her ancestors, Ka decides to set up the Phoenix Private Kitchen (a family-style eatery serving home-cooked meals).