Read the full text of Henry VI Part 1 with a side-by-side translation HERE.
The play starts off on a cheerful note with the death of Henry V, who is one of England's greatest heroes partly because he conquered France. Just as the English nobles are wondering how England will ever survive, a messenger comes to say that the French are rebelling and doing pretty well at it, too. The English aristocrats make plans to fight the French and protect young King Henry VI's kingdom. He needs protecting because he's literally a baby. Already, there are some signs that the nobility may not be able to get along well enough to save the day.
On top of all this, the French find a new champion, Joan of Arc. In some ways, she's more like Anakin Skywalker than Henry VI is. She comes from obscure origins (like Tattooine), seems to have supernatural powers (like being strong in the Force), and there's some ambiguity about whether she plans to use these powers for good. The French think she's a saint, which is a little bit like being a Jedi Knight, but the English think she's a witch, which in this culture is considered deeply dangerous, like being a Dark Jedi, or maybe even a Sith Lord.
Meanwhile, back at the ranch, the English nobility are fighting amongst themselves. Gloucester, the Lord Protector who's running the kingdom till Henry's old enough, has major conflicts with Winchester, who's sore because he thinks he doesn't get enough responsibility or respect.
A young man named Richard quarrels with an aristocrat named Somerset. Richard is about to be restored to his noble title, Duke of York, which his father lost by getting executed for treason. Not pretty, that—especially since we soon find out that Richard's family may have a better claim to the throne than Henry VI. If you're wondering what happens there, Henry VI Part 2 can fill you in. For the meantime, York and Somerset are bickering.
Henry VI makes it to France and is crowned king there, even though the English have lost a lot of France. It doesn't help that the quarrel between Richard and Somerset means they fail to get aid to Talbot, probably the strongest of the English military leaders, when he needs their help in a battle. He and his son die gloriously while fighting, but who's going to take their place?
Eventually, peace negotiations are begun by third parties (like the Pope). The English agree, and Gloucester negotiates a politically advantageous marriage with a rich noblewoman. Henry's not so sure about marrying this young, but if it's good for the kingdom, why not? He agrees.
Suffolk captures a woman named Margaret, whose father has some lands in France and is King of Naples. Suffolk thinks she's hot, but since he's already married he decides to try and set Margaret up with King Henry. Because that will end well.
Suffolk convinces Henry to dump his fiancée for Margaret, but Margaret has no money and less advantageous political connections. Gloucester is unimpressed and worried this will cause major problems for the kingdom. The play ends with Suffolk hatching a plan: He'll have an affair with Margaret, and that will let him influence her, which will let him influence the king. Yep, that should go well.