At Fife, in Macduff's castle, Lady Macduff is lamenting to Ross that her husband has run away, which, even if he wasn't a traitor, makes him look like a traitor. Also, abandoning his family with no defense is pretty lame. Ross assures her that her husband has his reasons.
Lady Macduff then has a funny bit of banter with her young son about how his father is dead. Before she can go to market to buy a new husband, a messenger enters advising her to flee with her children, as danger is fast approaching.
Thinking she has done no wrong, she sees no reason to leave, though she notes in these times one need do no harm to come to harm. A murderer enters, claiming Macduff is a traitor. Macduff's son retorts, is stabbed, and then dies, leaving the murderers to pursue his mother, Lady Macduff.