Micah returns silver to his mother, which she made into an idol.
The Danites find their homes (Judges 18) - In this chapter, the Danites find a home and settle it. They basically took it from the "quiet and secure" people of Laish.
The Danites were just looking for a new place to settlement. Perhaps they too had been displaced by the Philistines. After all, they had iron chariots, right? Not even Yahweh could stop one of those!
The Danites sent out five scouts who came upon Laish, and the scouts realized that the people of Laish were pushovers! They were "quiet and secure", and didn't even have a formal leader or magistrate. So, they look for a reason to conquer these people.
They find out that these people use idols! An ephod, a teraphim, a graven image, and - a molten image! I don't even know what a molten image, but the ephod is an ornate vest/apron. A teraphim is a small idol, or a 'household god', which would give good fortune to its owner. They just looked like small statues, basically. A graven image is basically a drawing. That's right - the Second Commandment is a rule against artwork.
Anyways, the scouts now have a reason and return to the Danite elite, telling them about the idols. They then send 600 guys out and they utterly slaughter the poor Laishites, and the Danites move in and settle.
Oddly enough, the Danites still use the graven image of Micah - and set it up "until the day of the captivity of the land."
This is odd, because the authors seem to have no problem with the Danites having an idol; though they just obliterated a small settlement for that very reason.