A case of leprosy, followed by umpteen assassinations. No wonder nobody reads this book in its entirety.
Jeroboam (the same one? The third? Who knows). Is a good king, except he doesn't dismantle the altars to Baal. Is anybody surprised at this point? So god strikes him with leprosy. He has to go to a leper colony and his son takes over.
His son is worse than him, and is assassinated. Then his assassin takes over the throne. He lasts a full month before he's assassinated and his assassin takes over. Finally, someone named Menahem assassinates that king and also massacres a coastal town that refuses to let him have sea access.
Menahem is a Baal worshipper and not only that, when the Assyrian king, Pul, invades, he pays him tribute, so much that he taxes all the wealthy men fifty shekels to pay it, but at least he leaves. He dies a natural death after 10 years and his son takes over, only to be quickly dispatched by the captain of his guards, who takes over as king. Then the Assyrians attack again and captures him. During the chaos, someone assassinates him and takes over the throne.
Meanwhile, Jotham takes over in Israel. He's a sinner, but he dies a natural death. God, though, is getting tired of all this disobedience and sends the king of Syria in to invade.