The whole of Hebrews deals with the perfection of Old Testament promises through the person and work of the Son of God. The first improvement treated in the book is Christ's supremacy over the angels. They are created beings, made to be worshipers, ministers of God. The Son, on the other hand, is begotten of the Father, King of all things, and eternal and unchangeable.
This sermon looks at the first plague with which God strikes Egypt. In chapter 5:2, Pharaoh denied even knowing God. The first plague brings him face to face with the God he has denied.