The Expanse is based on a series of novels written together by Ty Franck and Danial Abraham under the pen name James S.A Corey. The show stays pretty faithful to the books, with the plot beginning on an unspecified year in the 23rd century. In that setting, humanity has fully settled the Moon, Mars, and the asteroid belt. Earth is powerful but riddled with socio-economic and ecological issues, while independent Mars is growing in power and tending towards militarism. The asteroid belt is the poorest of the three, used by the inner planets as a cheap labor pool for extracting resources. The belters, those who live in asteroids and on space ships in the belt, want independence and dignity, while Earth and Mars want to maintain power and order in the solar system. The most unpredictable and violent factions of the belters have no issues with mass casualty terror attacks on Earth and Mars, leading to an inevitable cycle of violence that’s only exacerbated when alien technology becomes part of the story.
The show’s cast changed a lot over the course of the last six plus years. But the core remains Steven Strait, Dominique Tipper, Frankie Adams, Wes Chatham, Cara Gee, and Shohreh Aghdashloo. They all do a wonderful job portraying their respective characters, with former stars Thomas Jane, Cas Anvar, and Florence Faivre very much missed!