In the fall of 1907, Will and Eleanor Lightbody, a wealthy, neurotic couple from Peterskill, New York travel to Battle Creek, Michigan to immerse themselves in the routine of the famous sanitarium run by corn-flake inventor, Dr. John Harvey Kellogg. They meet Charlie Ossining who is seeking his fortune in the fickle market of Battle Creek's breakfast food industry. The Lightbodys have just lost their infant daughter and Eleanor is taking Will to the "san" for the cure. An inveterate meat-eater with a sexual appetite, Will was addicted, first to alcohol, and then, to opium, after his wife spiked his coffee with an off-the-shelf-remedy for drink.

At the sanitarium, they must occupy separate rooms, refrain from sex, and piously eat inflexible non-meat diets. Therapies include five daily enemas, exercises, "radiated" water, and an electrical "sinusoidal bath," which accidentally fries one of the residents. Kellogg is gravely disappointed in Will's inability to toe the "physiologic" line, but he is more deeply disturbed by his adopted son, George, whose chosen life on the street is a perpetual embarrassment.

Worried about his sexual prowess and deprived of his wife, Will becomes obsessed with his beautiful nurse and opts for the stimulation of an electrical belt; equally frustrated and bent on self-starvation, his wife turns to the quack "Dr Spitzvogel" who specializes in nudism and "manipulation of the womb." Brought to their senses by humiliation, Will and Eleanor go home.

Meanwhile, Charlie has joined with George Kellogg and borrowed from Will to keep his business afloat, but he realizes that he has been swindled. He only narrowly escapes jail, during a fiery commotion created by George who is then murdered by his adoptive father.