Zach Riley is a psychiatrist, who leaves a job at a prestigious university, to take up a job at the privately run mental institution, Millwood. What he doesn't reveal at the time of his appointment is that this was the very place where his novelist father, T.L. Pierson, spent many years of his life.
The year is 1955, and a great flood is coming to Northfork, Montana. A new hydroelectric dam is about to be installed in the mountains above the town, ready to submerge the valley in the name of progress. It is the responsibility of a six-man Evacuation Committee to relocate the townsfolk to higher ground. Most have duly departed, but a few stubborn stragglers remain – among them a priest caring for a sickly orphan, a boy whose fevered visions are leading him to believe he is a member of a roaming band of lost angels desperately searching for a way home.
With the aid of a fellow Auschwitz survivor and a hand-written letter, an elderly man with dementia goes in search of the person responsible for the death of his family.