"The castle of Macduff I will surprise, seize upon Fife, give to the edge o' the sword his wife, his babes, and all unfortunate souls that trace him in his line. No boasting like a fool; this deed I'll do before this purpose cool" Act IV Scene 1.
Lady Macbeth plans to drug King Duncan's guards to make them sleep, allowing Macbeth to enter Duncan's chamber and murder him in his sleep. She intends to place the blame on the guards to cover up their involvement in the crime.
Although she never out and says, "We should kill Duncan", it is implicit in many things she says.
kill him so macbeth can become king
Lady Macbeth uses flattery when she is trying to manipulate her husband, Macbeth, into going through with their plan to kill King Duncan. She praises his manhood and bravery to persuade him to take action.
Macbeth and Lady Macbeth plan to blame the murder of King Duncan on his chamberlains by framing them with the daggers used in the assassination.
Lady Macbeth wants to use their daggers to stab Duncan and then smear them with Duncan's blood. When Macbeth fails to do this, she does it herself.
Get the guards drunk and stab the king in his bed. It's not a complicated plan.
Macbeth and Lady Macbeth plan to murder King Duncan by inviting him to their castle as guests, then waiting until he is asleep to kill him. They plan to frame the chamberlains for the murder by planting the murder weapons on them.
Macbeth tells Lady Macbeth that he has decided not to go through with the plan to kill King Duncan.
Macbeth doesn't greet Duncan when he arrives because he is consumed by guilt and conflicting emotions about his plan to kill Duncan. His inner turmoil and ambition make it difficult for him to behave as he normally would.
The Prophecy says Macbeth will be king. Duncan is king. Macbeth cannot be king while Duncan is king. Duncan will not be king when he is dead. Therefore, make Duncan dead.
Lady Macbeth drugs the guards stationed outside King Duncan's chamber to ensure they are unconscious and unable to interfere with her plan to frame them for Duncan's murder. This allows Macbeth to easily access Duncan's chamber and carry out the assassination.
They plan to use the grooms' daggers and smear blood all over their hands, faces and clothes.
Lady Macbeth tells Macbeth that if they fail in their plan to murder King Duncan, they will simply try again until they succeed. She reassures him that their ambition and determination will ensure their success.
Lady Macbeth persuades Macbeth to follow through with the plan to murder Duncan. She calls him a coward and less than a man, prodding Macbeth to follow her plan. Macbeth agrees to murder Duncan that night.