Exodus

Exodus is the 2nd book of the Bible, and picks up immediately from where Genesis left off, with the descendants of Jacob in Egypt, due to the famine. Each of these 12 sons were the original 12 tribes of Egypt (except Joseph, whose two sons were each tribes of their own).  Immediately the story tells us of how the next generations of Egyptian rulers forget about Joseph and what he had done and make these Israelites their slaves.

Of all the books in the Old Testament, Exodus is one of the most well known.  Its name in Greek means "going out", and it subsequently tells of how God delivered the Israelites from slavery in Egypt to be a people of their own, called by God to be his chosen people.  (In Hebrew, the name of the book is actually "Names", because of how the book starts off with the list of names of the sons of Jacob.)

The over-arching structure of the book is something like this:

#1. Israelites are in bondage and early life story of Moses.
#2. God calls Moses to deliver them from Egypt, along with his brother Aaron.
#3. The series of plagues on the Egyptians, culminating in The Passover.
#4. The crossing of the Red Sea, and becoming finally free from the Egyptians.
#5. Entering Sinai, and the giving of the 10 Commandments as well as other laws, both moral, civil and ceremonial (religious), including establishing the priesthood (Aaron and his sons).
#6. People sinfully build a golden calf to worship, breaking God's law (and Moses literally breaks the commandments).
#7. Re-making the stone 10 Commandments, and further reminders of the laws of God.
#8. The building of the Tabernacle and Ark of the Covenant, according to the earlier commands God gave (#5).

The action oriented narratives are pretty familiar to most of us from the various movies made about the story.  Something those movie depictions don't always make clear, though, is how this event is what really makes the Hebrew people who they are.  Before this point, they didn't really have the Jewish religion or practices that we normally think of.  While God had already made covenant with Abraham and his descendants earlier in Genesis, it's only at this point where they get a cohesive set of laws and rituals (beyond just circumcision) which really sets them apart.  Much of Exodus (especially in the 2nd half of the book) is describing these laws and regulations (some in very exacting detail).

Exodus ends with the people still in the Sinai peninsula.  They won't reach the promised land for years to come.  But they now are a people free from slavery, and people of their own, with their own laws and religion, distinct from any other in the world.