The Expanse takes viewers across the solar system, introducing them to a humanity that has grown beyond Earth. However, mankind is far from united. The United Nations of Earth are wealthy and powerful, and have the most control in the solar system. Mars is an upstart colony trying to establish itself and create a haven for its people. The Outer Planets Alliance, or OPA, fights for the rights of the oppressed "Belters" who live on the impoverished stations of the Asteroid Belt. Shadowy corporations operate in secret, and tensions only get more heated when the "protomolecule" comes into play.