Dr. O'Neill

Dr. O'Neill is a fraud who approaches Monica Deane under the guise of a researcher interested in supernatural manifestations, while pursuing a concealed financial scheme. His apparent respectability depends on disguise: Monica recognizes him as the same man who had previously approached her under another identity, and the physical clues that betray him connect the supposed haunting to a plot against her.

The Proposed Purchase

Dr. O'Neill tells Monica that he belongs to the Society for Physical Research and has heard of the strange manifestations at her home. He offers to buy the house and conduct experiments there. The offer initially seems to provide a way out of Monica’s difficulties: visitors have been frightened away by the disturbances, and the small income on which she and her household depended has disappeared when the company holding it failed.

The apparent rescue is complicated by a prior approach from another buyer. Monica recalls that the earlier man was a sprucely dressed young man in his thirties, whereas Dr. O'Neill presents himself as a stooping, grey-bearded man of about fifty who wears glasses. The difference in age, appearance, and name is part of the disguise, not evidence of two separate buyers.

The Clues in His Disguise

Monica identifies the connection through details that remain visible beneath the changed appearance: both men have a gold tooth in the same position, noticeable when they laugh, and unusually shaped ears with hardly any lobe. The clues are small, but their conjunction makes coincidence implausible. Having noticed the resemblance, Monica delays answering Dr. O'Neill’s offer and seeks help from the International Detective Agency after finding its advertisement in an old newspaper used to line a kitchen drawer.

The case places physical appearance at the center of the investigation. Dr. O'Neill changes the broad signs by which strangers are recognized—his apparent age, beard, glasses, posture, and name—but fails to conceal the particular features Monica had already observed. His performance of the learned investigator is persuasive only until those details are compared with the earlier encounter.

The Scheme Behind the Haunting

Tommy concludes that Crockett, Monica’s maid, is involved and suspects that she has secretly admitted her nephew, who could then stage the disturbances while Monica was elsewhere with the household. He notices Crockett out of breath and interprets it as evidence that she has run down the back stairs after breaking a jug and basin. Dr. O'Neill’s interest in buying the property thus belongs to a larger attempt to exploit the manufactured haunting and Monica’s precarious finances.

When the Beresfords later test the supposed buyer, Tommy predicts that Dr. O'Neill will raise his offer. Monica receives word after dinner that the offer has increased by £150. The escalating bid strengthens the suspicion that the interest in the house is not a detached scientific inquiry. Dr. O'Neill’s false professional identity and the staged supernatural disturbances together provide cover for a scheme directed at Monica and her property.

Narrative Role

Dr. O'Neill’s role turns a seemingly supernatural problem into a question of observation and motive. Monica’s financial vulnerability makes his offer tempting, while the haunting has already driven visitors away; the promise to investigate the manifestations therefore arrives at the moment when a buyer could appear to be a solution. The repeated gold tooth and distinctive ears break through that reassuring story, making the supposedly different men legible as one disguised pursuer.

The character also belongs to the book’s recurring concern with performed identity. At the International Detective Agency, false names and convincing roles are part of the work; here the investigator’s professional appearance is itself a criminal mask. Dr. O'Neill’s disguise is not undone by a grand confession or a supernatural explanation, but by careful comparison of ordinary bodily details and by the rising price attached to the house.