In 1867, after his father's death and his mother's remarriage, fourteen-year-old Tyler and his black friend Isaac set out on the Missouri River headed west to seek their fortunes, encountering an unsavory keelboat captain and a Sioux Chief along the way. In 1867, after his father's death and his mother's remarriage, fourteen-year-old Tyler and his black friend Isaac set out on the Missouri River headed west to seek their fortunes, encountering an unsavory keel boat captain and a Sioux chief along the way.