After an initial historical review (chapters 1 through 9), the book of First Chronicles focuses on the reign of king David (also covered in Second Samuel).
The book of Second Chronicles covers the reign of David’s son and successor, Solomon. After Solomon, his son, Rehoboam, succeeds him as king, but following the bad advice of his peers, the nation is ultimately split in two. The smaller part (the tribes of Judah and Benjamin) is called Judah and is ruled by Rehoboam and his heirs (who are king David’s descendents). The nation of Judah is the focus of the remaining part of Second Chronicles, with only brief attention to what happens in their sister nation of Israel. Second Chronicles coincides with the events of First and Second Kings.
The nation of Judah is ruled exclusively by descendants of king David, some of who are good and godly rulers, others are not. Resulting from their reoccurring disobedience, they are conquered and all but the poorest people are deported to Babylon.
Most of the prophets lived during the timeframe covered in Second Chronicles. Their ministries and messages give additional insight into the reoccurring tendency of the nations of both Israel and Judah to turn their backs on God.