By Daniel James Brown, subtitle The Harrowing Saga of a Donner Party Bride.
The ugly truth: I paged right ahead to the cannibalism. Poor Mr. Brown spent months researching Sarah Graves's early life in Illinois, literally following in her footsteps on the emigrant trail, gathering and synthesizing documentation on the physiology of hunger, hypothermia, etc. etc., and I flipped past it all to get to the part where people start eating each other.
I'm no better than the romance readers who skip straight to the sex scenes. Maybe I'm worse.