And the king left ten women, which were concubines (2Samuel 20)

While 2Samuel chapter 20 is more action-packed than the previous chapter, there's not a lot here to cover. The fallout of the argument from the end of the last chapter is that a man named Sheba blows a horn and yells to the Israelites that David is clearly king of just the tribe of Judah, and the other tribes should abandon David, so they all leave. As almost a side note, David takes the ten concubines that Absalom had sex with and puts them away somewhere separate where he never has sex with them again.

David tells Amasa to assemble the troops and go after Sheba for being a troublemaker. They go after him, but on the way, Joab kills Amasa. (Joab really has this tendency to kill people who have offended him and/or David against David's will.) When they come to the city where Sheba is, they lay siege to it, and try to break down the wall. A woman comes to the wall and asks Joab what the meaning of the attack is, and Joab says that they really just want Sheba. So the people of the city chop off Sheba's head and throw it down to Joab. Joab blows a horn, and the army goes back to Jerusalem.