The Book of Jubilees, also known as The Little Genesis and The Apocalypse of Moses, opens with an extraordinary claim of authorship. It is attributed to the very hand of Moses; penned while he was on Mount Sinai, as an angel of God dictated to him regarding those events that transpired from the beginning of the world.
The story is written from the viewpoint of the angel. The angelic monologue takes place after the exodus of the children of Israel out of Egypt. The setting is atop Mount Sinai, where Moses was summoned by God. The text then unfolds as the angel reveals heaven's viewpoint of history.
We are lead through the creation of man, Adam's fall from grace, the union of fallen angels and earthly women, the birth of demonic offspring, the cleansing of the earth by flood, and the astonishing claim that man's very nature was somehow changed, bringing about a man with less sinful qualities than his antediluvian counterpart.
The story goes on to fill in many details in Israel's history, ending at the point in time when the narrative itself takes place, after the exodus. As a side note, the angelic dictation attempts to answer the question of how part of the Pentateuch was written by Moses after it records his death.