Where It All Goes Down
The Tabernacle near Mt. Sinai, circa the 12th-11th centuries BCE
Genesis takes us from the chaos of nothingness to the Garden of Eden, and from there, all over the map until the twelve tribes of Israel find a nice rental in Egypt. Exodus is a fiery whirlwind of adventure, taking the Israelites from Egypt to their thrilling encounter with God at Mount Sinai.
In Leviticus, the Israelites stay put.
Oh, sure, maybe they walk around a little, but just to the Tabernacle for sacrificial offerings and just outside the camp for everybody's favorite team building exercise, stoning a co-worker to death. Only two individuals go on anything close to an adventure: a goat that's sent out into the wilderness as part of the community's first annual atonement ritual and the guy who gets to take the goat out there (16:21-22).
While it might sound like kind of a let down, the Tabernacle setting is more than just a big tent surrounded by sand. The first verse of Leviticus starts with God speaking from the inside of the Tabernacle (1:1), and with that, the top of Mount Sinai has come down to earth.
It's a neat little rhetorical trick—from here until the end of end, the sanctuary is the voice of God (source). Instead of roaming around the Near East, the Israelites themselves will be living in one place, and God speaking from the sanctuary through his priests will help them live life there to the fullest.
The Setting Behind the Setting
There's more to the setting of Leviticus than meets the eye—at least according to those who don't believe that Moses wrote the book sometime around the 11th century BCE. A number of Leviticus and Torah scholars agree that priests most likely compiled Leviticus after Israelites returned from exile in Babylon during the 6th century BCE.
For believers dedicated to the worship of God in Jerusalem, the Babylonian exile was about as much fun as it sounds. Beginning in 597 BCE, the Israelites suffered a series of military defeats that led to their population being deported in waves to Babylon, a city-state located about fifty miles south of modern day Baghdad in Iraq (source). This left the exiles without a temple. A number of Jews assimilated to Babylonian life (ack—pagans!), and those who held on to the worship of God did so outside of priestly oversight.
They were doing their own thing, man, and there's nothing God's priests hate more than a bunch of sun-worshipping hippies dancing to the beat of their own drums.
This all gives the themes in Leviticus added oomph. The return from exile is a make or break moment for Israel: they either come together as a distinct community or fade away. Leviticus provides a model of how the Israelites can become—wait for it—one nation under God.