Lady Macbeth is alone on stage. She tells us that she drugged the King's guards and would've even killed Duncan herself, if he hadn't looked so much like her father in his sleep. Apparently, she's all family values now.
Macbeth enters with bloody hands and a weird story: two separate people staying in the castle woke up while he was in the act. One cried, "Murder!" but they both went back to sleep after saying their prayers.
Macbeth is disturbed that he couldn't say "Amen" when they said, "God bless us." He could have used the blessing, given how he recently damned his soul by killing the King.Lady Macbeth is of the "If you don't think about, it will go away" school of thought, but Macbeth is still clearly disturbed at having killed a sleeping old man for his own selfish gain.
There's also a little problem where he heard voices saying things like "Macbeth does murder sleep!"
Lady Macbeth tries to get her husband to focus on the matter at hand, which is framing the King's attendants.
He won't do it himself, so she takes the daggers from him, smears the attendants with Duncan's blood, and plants the weapons. Come on. That would never fool CSI: Cawdor.
As Macbeth philosophizes about his guilty hands, Lady Macbeth comes back, having done her part.
She hears a knock at the door, and hurries Macbeth to bed so that (1) they don't look suspicious, and (2) they can do a little washing up before all the "Oh no! The king is dead" morning hullabaloo.
Macbeth regrets killing Duncan —he says he wishes that all the knocking at the door would "wake Duncan" from his eternal sleep.Sorry, dude. No take-backsies with murder.