Mareun Gajie Baramcheoreom

As plague and turmoil afflicts the empire, enchanting widow Rieta Tristi finds herself at the mercy of a malicious nobleman and his dying wish to have her buried alive beside his corpse. The plague has taken her husband, slave traders have taken her young child, and now her own life is at risk -- until an unexpected visit from the empire's outcast prince changes everything.
(Source: WEBTOONS)
Note: Includes one extra chapter.