Gabriel Du Pré investigates a century-old crime. Lieutenant John Patchen has come to Montana to persuade Chappie Plaquemines, his former gunnery sergeant in Iraq and the son of Gabriel Du Pré's girlfriend, to accept the Navy Cross. First, however, Du Pré and Patchen must find the wounded marine, who was last seen drinking heavily in the Toussaint Saloon. They locate him soon enough, disheveled and stinking of stale booze, but a sobering visit to a medicine man's sweat lodge reveals a much greater mystery: the unsolved case of a band of Métis who were last seen fleeing from General Black Jack Pershing's troops in 1910 before disappearing. Strange voices within the sweat lodge speak of a place called Bitter Creek, where the Métis encountered their fate. To find it, Du Pré tracks down the only living survivor of the massacre, a feisty old woman whose memories may not be as trustworthy as they seem. But when Amalie leads Du Pré to Pardoe, an out-of-the-way crossroads north of Helena, he senses that they are about to uncover long-buried secrets. Discouraged by the US military, their lives threatened by locals whose ancestors may have played a role in the murders, Chappie, Patchen, and Du Pré bravely pursue the truth so that the victims of a terrible injustice might finally rest in peace.