In this chapter, men from Dan come by and steal Micah's idols and priest, and then go on to raze Laish.
This is another crazy chapter, lots of really questionable behavior from the Danites. Basically what happens is the men of Dan send out spies looking for a place to conquer, because "an inheritance had not been allotted to them" (v. 1). The inheritances were divided back in Joshua and Dan was assigned its land in Joshua 19. Possibly that means the events in this chapter happened before the land was divided by Joshua, or possibly it means they were assigned their land but couldn't take it and were now looking for an alternative. We don't really have any indication of the chronology of this chapter. With Samson and the other judges, it seemed like they were structured linearly so that one judge followed another. With the stories of Micah, that might not be the case because Micah isn't a judge. In fact, there aren't any more judges in this book. After the story of Micah is going to be another story of how the Israelites are harming each other and doing wrong. So it's possible this story (and the story in the next chapter) take place some time during or even before the judges started to rule over Israel.
Either way, the Danites seem to be pretty far out of where they should be, because their inheritance was given to them in the land of Canaan, near modern-day Gaza. This would be between Judah and Ephraim, to the west. Instead, we see them going up north of Ephraim to conquer Laish, which is near Sidon in the far north. In particular, the Danites are targeting a people who are "living in security", "quiet and secure", with only Sidon as their ally and no other allies. I.e. a peaceful land that would be unlikely to offer much resistance. Unlike Caleb, who asked to be given Hebron, which was populated by giants and large walls, the Danites are taking the path of least resistance, looking for a lightly armed and isolated city to butcher and take for their inheritance. And that is exactly what they do. Although they were conquering territory within the promised land, and to that extent were behaving properly, the Danites are hardly a model of faith like we saw in Caleb.
Verse 1 reminds us that there was no king in the land, and it is apparent that the Danites are not model citizens. After passing near Micah's house, they decide the best course of action is to steal Micah's idols and his priest and by inference, the LORD's blessing. In this, we can see that the Danites share Micah's attitude towards faith and God, which I talked about in the last chapter. They think that by stealing his ornaments of religiosity that God would bless them, and they couldn't be more wrong.
The priest seems to take a similar attitude. For him, joining Micah's family was an excellent job opportunity, but now came an even better offer, and so "the priest's heart was glad" (v. 20). In all of this, Micah, Dan and the priest all seem to treat religion as primarily a business interest. Micah and Dan sought God's blessing over their affairs, and the priest sought compensation in exchange for "providing" that blessing.
Basically the short version is that everybody in this story is doing something (or many things) wrong. That's why I called this chapter crazy, because so much of the stuff going on here is just wrong. Interestingly, the author of Judges does not explicitly condemn their behavior. His condemnation is implied through the phrase "In those days there was no king in Israel", but that is the extent that the author writes any personal commentary on what he is otherwise simply describing. But I don't think there can be any doubt that the Danites are being incredibly sinful, both stealing and worshiping an idol, both contrary to the ten commandments, and the author of Judges would have certainly been deeply familiar with the commandments. A while ago I wrote about how the OT does not always explicitly condemn things that are wrong, and that sometimes people mistakenly believe that implies assent. As we can see in this chapter, it does not.
After his priest is stolen, Micah goes to recover his belongings and is promptly threatened by the Danites. Lacking military force, Micah goes back home to mope. And with that, we won't see Micah in the rest of this book.
I think this story (and the story in the previous chapter) is really interesting because it gives us a view into "what life was like when there was no king". Most of Judges is writing about the exploits of these great heroes, like Gideon or Deborah, or less heroic figures like Samson. This chapter is about a man who isn't a judge at all, he's just an ordinary Ephraimite trying to make a living in their newly conquered home. It provides an interesting perspective because it shows us how some of the Israelites were living at that time. Of course, these stories were selected by the author to prove a point, so it might not be representative of what all Israel was like. But I think the author is trying to say, "before there was a king, people would do all kinds of crazy stuff, steal from each other by force, lie, make idols, steal idols, and they thought God would bless them for it." And as I said, they couldn't be more wrong in this attitude.