Act One is the introduction of the characters, the plot and the different conflicts that will develop throughout the play.
In the first scene the audience is introduced to Richard Gloster and the conflicts which will be dealt with throughout the play. Gloster gives a short speech detailing his plot against his brother Clarence, who comes before him as heir to the throne of England. Richard has just succeeded in having Clarence arrested and it as a prisoner that Clarence walks onto the stage, guarded by Brackenbury. Clarence has been arrested because King Edward, who believes in a lot of prophecies and omens, was told that a person with a name starting with the letter "G" would cause his family to lose the throne. Since Clarence's full name is George, Duke of Clarence, he was considered to be the primary suspect. Gloster states his belief that his could be the result of women plotting against Clarence, most likely Queen Elizabeth and Mrs. Shore. Brackenbury takes Clarence into the Tower of London. Gloster promises that he will soon remove Clarence permanently and thus clear the path to the throne for himself. Lord Hastings, also known as Lord Chamberlain, emerges from the Tower, having just been freed. Lord Hastings tells Richard that King Edward IV is sickly and ailing, and cannot hope to live much longer. After he departs, Richard remarks that he will first have Edward kill Clarence. This will put Richard into a position where upon Edward's death he can assume the throne. He also plots to marry Lady Anne Neville, who is the widow of Edward, Prince of Wales and the daughter-in-law of Henry VI, whom Richard just killed.
Lady Anne enters the scene accompanied by pall bearers who are carrying an open coffin with King Henry VI in it. She asks the men to stop, during which time she laments the death of the king. Lady Anne then curses any future children which Gloster might have, and prays that after Gloster's death his future wife will know even more grief than Lady Anne currently feels. Gloster enters and is immediately Lady Anne curses him for his role in the death of her husband. He tries to woo her by telling how lovely he thinks she is, but she scorns him after each attempt. He finally tells her that he killed her husband so that he alone could love her. He then bends down on his knees and tells her to kill him if she cannot forgive him. She attempts to kill him but find it in herself that she cannot. He proposes marriage to her, succeeding in making Lady Anne wear his ring. He tells her to go wait for him in one of his London residences while he mourns the death of Henry VI. Lady Anne leaves after saying farewell to Gloster, who delivers a soliloquy in which he expresses surprise about the fact that she seems to like his looks.
Queen Elizabeth enters the scene with Lord Rivers and Lord Gray. They begin to discuss the fact that King Edward is ill. Queen Elizabeth is fearful about her future if he should die. She remarks that Gloster becomes her son's Protector if Edward passes away. This worries her because he does not like her or her companions. The Duke of Buckingham and Lord Stanley arrive, they have just been to see the King, and they inform Queen Elizabeth that he is looking well. Buckingham informs her that the King would like to meet with her brothers and Gloster in order to get them to make peace. Gloster and Lord Hastings enter the room, with Gloster complaining angrily about the lies which "they" tell the King. When asked who "they" are, he implicates the queen's brother, Lord Rivers, and her two sons. He then blames them for the recent imprisonment of Lord Hastings, and for the current jailing of his brother Clarence. Queen Elizabeth is outraged at these accusations, and threatens to tell the King.
Queen Margaret arrives; she is the widow of Henry VI and the mother of Edward whom Richard killed. She speaks directly to the audience, without the other characters hearing her, where she explains that Queen Elizabeth has her to thank for the throne, and calls Gloster a devil for the murders he has committed. Gloster defends himself strongly, pointing out his fierce loyalty to his brother Edward. He then points out the fact that the Queen and her brother fought against his brother in the war between the House of Lancaster and the House of York, to which he belongs. Queen Margaret, fed up with the arguments and accusations, steps forward and addresses them all. She plans to tell them once again about how Gloster killed her son Edward, but all of the gathered characters attack her for having killed Rutland. This refers to a previous play in which Margaret crowns the Duke of York with a paper crown and waves a handkerchief dipped in his son Rutland's blood in front of his eyes. She tells them that because her Edward died, so too must the current Edward, Prince of Wales meet his death.
The entire company is then summoned into King Edward's chambers. Gloster remains behind and meets with two murderers whom he sends to kill Clarence. A revealing quote is when Richard says, "And thus I clothe my naked villainy with odd old ends, stolen forth of Holy Writ," meaning he disguises his crimes with Christian behavior.
Clarence and Brackenbury enter the scene where Clarence has had a terrible nightmare in which he breaks free of the Tower and attempts to cross to Burgundy accompanied by his brother Gloster. While on the ship, Gloster stumbles. When Clarence tries to help support him, he is flung into the ocean by Gloster, where he slowly drowns. Clarence falls asleep with Brackenbury sitting next to him for protection. The two murderers sent by Richard arrive and hand Brackenbury their commission. He acknowledges the paper which says to hand his prisoner over to the two men. One of the murderers has a sudden attack of conscience. He is able to overcome this by remembering the large reward which Richard is paying him. The second murderer tells his companion to drive the devil out of his mind, since the devil is only confusing him. Clarence wakes up and asks for a cup of wine. The murders inform him that Clarence that he will die. He pleads to their sense of Christianity, at which they list his many sins, most notably the killing of Henry VI's son Edward. Clarence then begs the men to talk to Gloster, whom he promises will reward them handsomely. They inform him that Gloster is the man who sent them, a fact that Clarence cannot believe. He seems about to overcome them with his persuasive words when the first murderer stabs and kills him. The second murderer refuses to participate, and even declines to receive his part of the reward.