Act Four, Scene One
Queen Elizabeth, the Duchess of York and Lady Anne (now Richard's wife) ask to be let into the Tower to see Prince Edward and young York. Brackenbury forbids them to enter, saying, "The King hath strictly charged the contrary" (4.1.17). He realizes his slip of the tongue and corrects himself by saying, "I mean, the Lord Protector."
Stanley enters and orders Lady Anne to Westminster Abbey, where she is to be crowned queen. Queen Elizabeth, realizing that Richard has succeeded at seizing the throne, orders her son Dorset to go to Henry Tudor, Earl of Richmond. Stanley agrees with her and sends the young man away. Elizabeth decides to return to sanctuary, while the other women choose to flee to Richmond.
Act Four, Scene Two
King Richard asks Buckingham if he will support him in killing Prince Edward. Buckingham is reluctant, and begs for a while to consider the issue. Richard thinks that Buckingham is too ambitious, and becomes suspicious of him.
Richard then calls a page over, and asks if the man know anyone willing to kill for a sum of money. The page tells him that a man named Tyrell would be happy to serve him. Richard then tells the audience that he is plotting to kill Buckingham.
Next he speaks with Catesby, telling him to start rumors that Lady Anne is ill. Richard also plans to marry Clarence's daughter to a non-nobleman, but will let her brother Edward live since he is "simpleminded."
Tyrell is being dispatched to kill the two young boys still living in the Tower when Buckingham arrives. Buckingham asks Richard for the Dukedom he was promised earlier in the play. Richard instead talks about the fact that Richmond is prophesied to become the king, and that he was told he would not live long after seeing Henry Tudor's face. Buckingham continues asking, but Richard then remarks that he is not in the "giving vein." Buckingham realizes his life is in danger, and prepares to flee.
Act Four, Scene Three
Tyrrell, the murderer sent by Richard to kill the Edward's children, returns having done the deed. He tells Richard that they are dead, and is invited to dinner that night in order to tell how he killed them.
Ratcliffe enters running, and informs Richard that the Bishop of Ely has fled to join Richmond, while Buckingham has started raising an army. Richard is shaken by the fact that all of his top lieutenants are either dead or have fled from him. He orders his armies to be quickly assembled so that he can overcome his traitors.
Act Four, Scene Four
Old Queen Margaret emerges and says that she has patiently watched the destruction of her enemies. She informs the audience of her plan to go to France where she hopes to see the few remaining enemies die tragic deaths. She then tells Queen Elizabeth that her curse is coming true, and that she is being revenged for her losses. Elizabeth begs Margaret to teach her how to curse, so that she too may have revenge.
Richard enters and is immediately abused by the women present. His mother, the Duchess of York, demands that he listen to her, which he unwillingly does. She finishes her remarks with a curse on Richard, namely that he should die in the battles he is about to fight.
Richard then speaks with Queen Elizabeth. He tells her that he wants her daughter Elizabeth to be his queen. She scorns his suggestion, and tells him to write her daughter a letter describing all of her relatives that he has killed. Richard does not like the way she mocks him, and continues pleading with her to help him win her daughter's hand. She finally agrees to go talk with her daughter, and Richard assumes that he is victorious.
Ratcliffe enters and tells Richard that Richmond is already arriving with ships on the western shore. Richard, in the first moment of confusion he has ever shown, hastily issues orders and then is forced to contradict himself. He states, "My mind is changed" (4.4.387)
Stanley enters and informs Richard that Richmond is almost upon them. Richard accuses him of treachery, and orders him assemble an army. Stanley, in order to prove his trustworthiness, allows Richard to keep his son.
Several messengers arrive and give both mixed good and bad news. Richmond manages to finally land at Milford, a relatively unpopulated area which is ideal for and invading army. However, Catesby enters the scene to tell Richard that Buckingham has been captured.
Act Four, Scene Five
Stanley tells a priest to go to Richmond and inform him that Stanley is unable to join his side because Richard is holding Stanley's son in custody. He also mentions that Queen Elizabeth has agreed to let Richmond marry her daughter once he defeats Richard.
Margaret's curse in the first act becomes more powerful by this point in the play, for several of the characters she cursed to die have in fact been killed. Both Rivers and Gray die by invoking Margaret's curse, and say that after them will come Hastings, Buckingham and finally Richard. This is once again invoked by Margaret when she demands a "right for right" (4.4.15). Thus the play really does turn into a revenge play in its final moments, as a result of the invocation of talionic justice.
The Duchess of York also learns the ability to curse in this portion of the play. Note how her language changes from smooth passages to stichomythic lines. She essentially becomes a similar character to Margaret, and thus is able to put a curse onto Richard, telling him that, "Bloody that art, bloody will be thy end; / Shame serves thy life, and doth thy death attend" 4.4.195-196)
The most important aspect of Richard's personality to recognize is that now that he has become king, he starts to fail. Indeed, it is the moment he takes the crown that he is unable to command every situation. The reason for this change lies in Richard's personality: he is entirely antagonistic, and cannot be the protagonist.
This is evidenced by his command to kill the young sons of Queen Elizabeth. He already has the throne, and the boys are certainly no threat to him since he has bastardized their birth. Thus, the killing is entirely gratuitous. For the first time, Buckingham refuses to jump up and obey Richard, instead pausing to consider the act and then refusing to participate. Probably the surest sign of Richard's demise is the fact that he then calls a page over, a young boy, so that he can hire a murderer to carry out the deed. The use of a page implies that Richard's court is entirely confused and has no structure at this point.
Another obvious sign of Richard's decline in power is the defection or death of all his top lieutenants. This directly comes from Margaret's curse, where she says that he will kill his friends as traitors (Hastings) and make traitors his friends (Stanley). With the defection of Buckingham it soon becomes obvious that Richard is doomed. His top men are now Catesby and Ratcliffe, both of whom are minor men within the play.
Even more telling is Richard's inability to command the situations he is in. This act marks his second attempt at a seduction, in this case Elizabeth. However, for the first time he fails, and cannot win her over. And instead of promising him her daughter, she is able to put him off. Richard interprets this as a victory, again showing that he has lost control of the situation.
The next scene which marks the complete degeneration of Richard's control over the action is when Ratcliffe and Catesby come to tell him about Richmond's navy. He issues orders to Catesby to "fly to the Duke" and orders Ratcliffe to head to Salisbury. Both men remain standing, at which Richard cries, "dull, unmindful villain, / why stay'st thou here, and goest not to the Duke?" (4.4.376-377). Catesby asks him, "What from your grace I shall deliver to him?" The action ends with Richard remarking, "My mind is changed" (4.4.387). Indeed, his mind is no longer the same, and he is unable to stay three steps ahead of the other characters as he initially did.