In the midst of a World War, the true enemy was unseen. It came with a handshake or a breath and it left behind 60 million dead. Spanish Flu would devastate the world.

Dr. Alan Keener is a young doctor fresh out of medical school who suspects that the Spanish Flu has reached his hometown of Cumberland, Md. He wants to take steps to prevent its spread, but he is met with resistance from old-school doctors who believe the flu's deadliness is overblown and easily treated.

They soon learn differently as the flu begins spreading, aided by a street preacher named Kolas. During the delirium caused by his own bout with the flu, he believes that he was anointed as the wrath of God and must spread the flu to bring God's retribution to the world.

Alan and the other doctors race to find a way to treat the overwhelming number of sick and dying. They are already short-staffed because of the war, and now nurses and doctors begin to fall ill and die, making the crisis worse.
The fight becomes personal for Alan as his daughter and then his wife become ill with the flu. Can he find a treatment to keep them alive or will they become two of millions dying from Spanish Flu?