Abijam is a sinful king just like his dad. Still, because his great-grandpa David was so righteous (except for that whole Uriah the Hittite thing), the Lord preserves his lineage.
The war between Israel and Judah continues throughout Abijam's life, and then he dies.
His son Asa becomes king, and he is actually a good guy. He takes away all of the idols and temple prostitutes, and even takes away his mom's (or grandma's?) crown because she is an idol-worshipper. Way to clean house, Asa.
He doesn't go so far as to tear town the pagan temples, but he still manages to remain pure of heart for all his days, and fills the temple with lots of gold and silver and other treasures.
(Note: For some reason, verses 16-24 occur chronologically after verses 25-33. We'll go ahead and tell them in order.)
When Jerry's son Nadab becomes king, he's evil just like his dad.
He goes to war against a city called Gibbethon, and during the siege a guy named Baasha—who's a son of Ahijah—kills Nadab.
So now Baasha is king, and he kills the whole house of Jeroboam, just like Ahijah prophesied would happen (back in chapter 14) because of Jerry's wickedness.
Now Baasha and Asa are at war. Baasha takes over a city called Ramah and builds a fortification there to block the road into Jerusalem.
So Asa sends all of the treasures in his house to Ben-hadad, the king of Syria, and asks him to assist in the war against Israel. Ben-hadad agrees and sends his armies against the cities of Israel.
Baasha withdraws from Ramah and Asa dismantles it stone-by-stone and timber-by-timber. He uses these materials to build new cities.
Asa gets old, and his feet get diseased. Then he dies, and his son Jehosaphat assumes the throne.