After being elected state senator, Bill Henrikson announces that he is a polygamist, and he and his families are attacked from every side; Alby Grant returns from living in the desert with the idea of purifying the compound and getting revenge.

After revealing his polygamy to the world the newly elected Bill goes even further out on a limb by calling publicly for more polygamists to come into the open while Barb talks Nancy, her mother, into attending a mother-daughter symposium.

The Henricksons' holiday cheer is tested by family revelations. Alby's purification of Juniper Creek leads to a defection.

Bill fights for his right to be sworn in as senator; Barb, Nicki, and Margene struggle with personal revelations and changed public profiles.

Bill finds success in the Senate but finds new roadblocks set up by the Mormon church. Barb comes to a new conclusion about her life. Cara Lynn's adoption faces a new obstacle. Lois recalls her past with Frank.

Bill refuses to give in to Barb's vision of the church; Nicki chafes at the status quo; Margene looks to rally the children of polygamy.

Bill fights for his family and his freedom; Alby looks to settle unfinished business; Nicki plans a new future for Cara Lynn.

Alby gets Adaleen on his side against Bill and his family. Rhonda asks Ben to marry her which results in Ben & Heather breaking up. Bill faces the possibility of a 20 year sentence, as his family tries to cope. Cara Lynn breaks down after Nikki tells her that Mr. Ivy never loved her.

In the series finale of Big Love, Margene plans on going on a cruise by herself to help people, Barb prepares to get baptized in the new church, and Nikki fears that she will be left alone if Bill goes to prison.