Nathan the prophet comes to David with the news about two men who live in the town: one rich, one poor. The poor man had a lamb that he raised as one of his own children, not unlike many pet owners today. A traveller came to town recently and stayed with the rich man, who, rather than feeding him one of his own flock, killed the poor man's lamb.
David, clearly not a Republican, is incensed, and orders the poor man's flock restored fourfold. But wait! It's a parable! Nathan points out that David is the rich man, because of this whole Bathsheba incident. His punishment will be to have his wives taken away and given to his neighbour, who will then publicly consummate the marriages.
David is contrite, but Nathan says god has already forgiven him, but his son is going to die. Well, that seems fair. Lo and behold, the boy Bathsheba was pregnant with in the last chapter is sickly and no amount of praying and fasting can save it. It dies after a week.
David gets up then and washes, prays and takes food again. David points out that now that the kid is dead, there's no point hastening his own demise. He even starts having sex with Bathsheba again, resulting in Solomon. God loves this baby and calls him Jedediah.
Meanwhile, Joab is still fighting the Ammonites and trying to conquer Rabbah. David goes to his assistance. Upon winning, he takes the king's heavy crown and the rest of the spoils. Depending which translation you believe, he then either has the people tortured or enslaved.
Next chapter: sibling rape goes wrong.