Lady Macduff's is conversating with her son about how his Father is dead. He rebuttals her saying he knows his father is not dead.
Malcolm suggests finding a nice shady spot where they can cry their eyes out. Macduff's got a better idea: maybe they should whip out their swords and fight like men against the good for nothing Macbeth.
Macbeth see's 3 apparition's. First, an armed head warns him to beware of Macduff. The second apparition is a bloody child who says that Macbeth won't be harmed by anyone who was "of woman born." . Macbeth welcomes this good but figures he might as well have Macduff killed anyway.The third apparition is a child wearing a crown and holding a tree in his hand. The child promises that Macbeth won't be conquered until Birnam Wood marches to Dunsinane.
Murderer's break in and kill Lady Macduff's son.
Macduff tells Ross not to be stingy with his words. It feels like he's holding back. So Ross tells him that the rumor is that if Macduff were to return to Scotland, a whole lot of men and women would be willing to take up arms against Macbeth.