A young doctor returns to his New England home town and visits with the kindly old town doctor. He begins noticing there are two sorts of patients in the town doctor's practice: very healthy ones, and sickly ones who somehow don't respond well to treatment and die during the young doctor's visit. Nosing around the old doctor's clinic, the young doctor finds an unusual number of poisons in the dispensary room... and suddenly begins noticing subtle, then not-so-subtle incidents which culminate in attempts on his life. I won't disclose the ending, even though it's permitted here, because it's pretty good and you deserve to see it without it being "spoiled."