On their way to a town where there are rumors of a Big Death vaccine, Jeremiah and Kurdy meet William and his pregnant wife, Paula. Paula is running a fever and is in serious need of a doctor. The town is told they are in luck as a travelling doctor named Reese has just arrived, though the huckstering welcome given by the doctor's brother Jake does not inspire confidence. It soon becomes clear that Reese has learned something about being a doctor from an old medical text, a doctor's bag and the very few years of watching his father, an actual doctor, work. Whether Reese himself has learned enough to perform doctoral duties is one question. Whether he will defy his brother and accept responsibility is another.

As Reese tends Paula, Jeremiah and Kurdy set out to find their next contact, Holcomb but only find his girlfriend, Sadie. Holcomb is out of town and seriously ill. Sadie offers them all a place to stay, if only as a way to keep the doctor near until Holcomb returns.

In the middle of the night, Jeremiah wakes to find the brothers gone. He and Kurdy head out in pursuit and find them, badly beaten and robbed of all their possessions - including Reese's medical bag. Without his bag, Reese's confidence is utterly gone. Kurdy takes Jake and goes in search of the bag. At Sadie's, a drunken Reese whines about how hard life is. Jeremiah cuts into him, revealing the tragic secret of his own brother's death.

Kurdy and Jake battle the thieves and recover the bag and by the time they return, Reese has found something better - himself. His new confidence is enough to save Paula and her baby but not enough to save Holcomb. Holcomb is dying from the effects of the experimental vaccine but the task he sets Jeremiah and Kurdy may help save others if, or when, the Big Death returns.