What's Going on in Exodus 28?

Aaron and his sons shall tend it from evening to morning before the Lord, which brings us right into Exodus 28. The robe and the ephod, Aaron is to wear them when he ministers; these bells are to be on his garments so that they can be heard at holy places. And I think the implication is if he does not follow these regulations, then what happens to Nadab and Abai who could happen to Aaron. It's a warning that Yahweh is serious about these instructions. If you violate these instructions, death could be the result.