"If you could have been in the (Salt Lake City) Tabernacle on Aug. 16, 1857, and heard Brigham Young speak. ... It was virulent hate speech," said historian and author Will Bagley. "It was violent, it was bloody, and it was apocalyptic."

Most of Young's dialogue was drawn directly from the church president's speeches, Cain said.

"Look. It's an ugly, dark day in their history and it happened and it needs to be understood," he said. "If they can take a look at it for what it was and not project it to how the Mormon church is today, they can get past it, it can be opened up, dealt with and gone."

Survivor descendant Bob Fancher of Joplin, Mo., hopes the movie will correct the historical record and foster an opportunity for discussion.

"The church ought to admit, 'Yeah, we had some people and some leaders that did this,' and let's just get it out in the open," said Fancher. "I don't need an apology."

After 150 years, it would be nice to lay the issue to rest, Kimball added.

"Not in the sense that we're trying to hide it," he said. "But to finally tell the truth about our role in this horrible thing, so that we can tell our children we did the honorable thing."