Mrs. Ferguson is a vampire.

There should be no doubt about this: two reliable eyewitnesses have observed her, on separate occasions, sucking blood from the neck of her infant son. “On one occasion … this child had been left by its nurse for a few minutes. A loud cry from the baby, as of pain, called the nurse back. As she ran into the room she saw her employer, the lady, leaning over the baby and apparently biting his neck.” Apparently? Surely more than that: “There was a small wound in the neck from which a stream of blood had escaped.” The mother bribes the nurse to keep quiet about what she has seen, a gesture difficult to interpret otherwise than as an admission of guilt. From then on the nurse closely watches the mother, the mother closely watches the nurse, and both closely watch the baby. “Day and night the nurse covered the child, and day and night the silent, watchful mother seemed to be lying in wait as a wolf waits for a lamb” (“SV,” p. 537). Or as a vampire waits for her prey.

Fearing for the child's life, the nurse confesses everything to Mr. Ferguson. Convinced that his wife is as devoted a mother as she is a loving spouse, and outraged by the nurse's scandalous accusation, he scornfully tells her “that she was dreaming, that her suspicions were those of a lunatic, and that such libels upon her mistress were not to be tolerated” (“SV,” p. 537). Moments later, however, the evidence of his own eyes leaves him no choice but to believe the nurse's wild story.