"The Best Land Under Heaven: The Donner Party in the Age of Manifest Destiny" by Michael Wallis. My rating: 5 out of 5 stars. Published in 2017.
Book description: In the spring of 1846, a restless caravan prepared for what they hoped would be the most rewarding journey of a lifetime. But in eagerly pursuing what would a century later become known as the "American dream," this optimistic-yet-motley crew of emigrants was met with a chilling nightmare; in the following months, their excitement would be replaced by desperate cries for help that would fall silent in the deadly snow-covered mountains of the Sierra Nevada. We know these early pioneers as the Donner Party, a name that has elicited horror since the late 1840s. This is an account” (of the notorious saga which recounts how the unlikely band of early pioneers met their fate.
This book is detailed and graphic. It is much more than the overview written in the school history textbooks I read.