The action takes place in Scotland, at a wayside station; in Dr. Macfarlane's old consulting room; and at the Crosskeys Hotel, Kilringen, in the year 1924.

Dr. Knock has been sold a pup. He has bought Dr. Macfarlane's practice at Kilringen and speedily he discovers that it is a practice as shaky as the ancient and temperamental car in which he is being taken, spasmodically, to his new domain. Briefly, there are no patients: the inhabitants are disgustingly healthy and not given to seeking a doctor's aid.

But Dr. Knock is resourceful-and he has a method so startling as to be unique. By employing it he is sure that he can turn a barren practice into a doctor's Eldorado. The age of medicine, to use his own words, can now begin.