Vin is a Skaa thief who was abandoned by her brother while in a crew in the capital city of Luthadel. She unknowingly is using her Mistborn powers in the Ministry, so they try to follow her to kill her. A thief crew led by Kelsier find her and protects her from the Ministry. Kelsier recruits Vin into his crew with the intention of overthrowing the Final Empire led by the immortal Lord Ruler.
Over time Vin practices and gets good at using her Mistborn powers. She is more powerful than Kelsier even though she is newer at it. She is sent to pretend to be a Noblewoman, and starts a relationship with Elend, the heir to the most powerful of the great houses, House Venture. Sazed is a Terrisman Feruchemist who helps Vin learn to act as a Noblewoman. Vin goes to the balls of the great houses to gather information. Over the course of about a year, the crew is able to start the great houses fighting a civil war amongst themselves, and raise an army. Near the end the army decides to go fight on their own and gets crushed, but draws out the main city Garrison.
Kelsier's brother Marsh goes to inflitrate the Steel Ministry, and ends up being turned into a Steel Inquisitor. Kelsier, thinking Marsh is dead, gets angry and destroys the Atium mine. In retaliation the Lord Ruler starts killing Skaa and Kelsier fights back. He kills an Inquisitor, and then is killed personally by the Lord Ruler. That night a shapeshifter pretends to be him to stoke the city population to rebel. Kelsier becomes known as a religeous figure and as The Survivor. They overthrow the government while Vin goes in to fight the Lord Ruler. She discovers that he is really a Feruchemist and he stores health to stay alive forever. She Pushes his metal bands out that store his health, and he rapidly dies of old age. Elend becomes the new King of the city.
Skaa are the lower class with no rights that can be murdered whenever and however by the Nobleman. There are Mistborn who can use any metal for super powers and Mistings who only have one power. Only Nobleman have powers, so the Skaa who are Mistings are really half bloods. Nobleman are required by law to kill any Skaa women they have sex with so that aren't any half bloods with powers running around, but some still happen. Mistings/Mistborn are also called Allomancers, and the power they use is called Allomancy.
The Lord Ruler is the immortal "God" who rules over the Final Empire which spans the entire known world. He is really just both an Allomancers and a Feruchemist so he can store health infinitely to stay alive no matter how badly he is hurt. He uses the Nobleman to rule over the Skaa and the Ministry to keep the Nobleman in line. He has Steel Inquisitor's who can track down and kill any Allomancer, and Kablos who are inhuman creatures that can crush any army that tries to fight back.