Exposition (Initial Situation): Wedding Bells Mark the End of an Era
Not everyone's excited about Henry's marriage to Margaret. For one thing, it comes at a hefty price: England has to give up some lands in France. This starts some grumbling in the palace between the nobles: on one side, we've got Cardinal Beaufort, Buckingham, Somerset, and Suffolk, and on the other side, we've got Salisbury, Warwick, and York.
And then there's Gloucester, the thorn in everyone's side: he's a problem because he's got so much power over Henry and England. Even his wife, Eleanor, thinks she should become queen.
Rising Action (Conflict, Complication): Thunder, Lightning, and Pain
Eleanor has dreamt of becoming queen, and she wants to talk to some conjurers and witches to see if it's true. Her excitement over the thunder, lighting, and prophecies they tell her is short-lived: she's arrested by York, Suffolk, and Somerset for witchcraft. She is publicly shamed and banished, while the rest of the gang involved is killed.
Gloucester mourns over his wife's predicament. He wants to help her, but he knows she's done wrong. It doesn't matter much, anyway, because Gloucester's own enemies arrest him for treason and take him before the king. Still, Henry believes that Gloucester is innocent and will allow him a trial to prove it.
Climax (Crisis, Turning Point): Speak No More
Suffolk, Cardinal Beaufort, and Margaret all conspire to kill Gloucester. It doesn't matter that he's not guilty of anything—they just want him gone. They hire some murderers, who faithfully carry out the deed.
Henry learns of Gloucester's death and mourns for his friend. Warwick points out that Gloucester died under suspicious circumstances, and he eventually accuses Suffolk and Beaufort of his death. Henry is grief-stricken. The people start to revolt, demanding to know who killed Gloucester and why. Henry can't seem to control the people, his nobles, or even his wife.
Falling Action: That's One Block-Cade
York has hired Jack Cade, a commoner, to stir up trouble in London while he's away. Cade will claim to be Mortimer, a noble in line for the throne. (Mortimer is actually dead, so no one will know he's not the real deal.) Cade raises an army of commoners by saying that when he rules, every man will have a say, and people won't get arrested for being illiterate. He takes down Henry's armies on London Bridge and at the Tower, and he keeps going strong until he realizes that his men are as fickle as can be. He's got nothing left to do but run away.
Resolution (Denouement): Won the Battle—How about the War?
Cade is captured and killed when he won't back down. York starts storming his way to London with his army, but he's stopped by Henry's men, who demand to know what he's up to. At first, York lies and says he just wants to kill the traitor Somerset. But he loses his cool pretty quickly and starts fighting Henry's men right then and there. He kills Clifford, and Richard kills Somerset.
Seeing that he is losing, Henry flees to London, where he has more support. York declares victory and promises to meet Henry in London to finish the war.