Chase walked deliberately over to Kennedy and handed him something, while the nurse glanced calmly, almost with pity, at Mrs. Wardlaw, ignoring Wardlaw, then fixing her gaze venomously on Miss Langdale.  Recalling the incident of the morning, I was ready to prevent, if necessary, a repetition now.  Neither moved.  But it was a thrilling, if silent, drama as the two women glared at each other.

Kennedy was hastily comparing the anonymous note he had received with something Chase had brought.

“Some one,” he shot out, suddenly, looking up and facing us, “has, as I have intimated, been removing or destroying the vital principle in the food—­these vitamines.  Clearly the purpose was to make this case look like an epidemic of beriberi, polyneuritis.  That part has been clear to me for some time.  It has been the source of this devilish plot which has been obscure.  Just a moment, Kato, I will do the talking.  My detective, Chase, has been doing some shadowing for me, as well as some turning over of past history.  He has found a woman, a nurse, more than a nurse, a secret lover, cast off in favor of another.  Miss Hackstaff—­you wrote that letter—­it is your hand—­for revenge—­on Miss Langdale and—­”

“You shan’t have him!” almost hissed Helen Hackstaff.  “If I cannot—­no one shall!”

Natalie Langdale faced her, defiant.  “You are a jealous, suspicious person,” she cried.  “Doctor Aitken knows—­”

“One moment,” interrupted Craig.  “Mrs. Marbury is gone.  Mrs. Wardlaw is weakened.  Yet all who are affected with nerve troubles are not necessarily suffering from polyneuritis.  Some one here has been dilettanting with death.  It is of no use,” he thundered, turning suddenly on a cowering figure.  “You stood to win most, with the money and your unholy love.  But Miss Hackstaff, cast off, has proved your Nemesis.  Your nervousness is the nervousness not of polyneuritis, but of guilt, Doctor Wardlaw!”

IX

THE RUBBER DAGGER

“Hypnotism can’t begin to accomplish what Karatoff claims.  He’s a fake, Kennedy, a fake.”

Professor Leslie Gaines of the Department of Experimental Psychology at the university paced excitedly up and down Craig’s laboratory.

“There have been complaints to the County Medical Society,” he went on, without stopping, “and they have taken the case up and arranged a demonstration for this afternoon.  I’ve been delegated to attend it and report.”

I fancied from his tone and manner that there was just a bit more than professional excitement involved.  We did not know Gaines intimately, though of course Kennedy knew of him and he of Kennedy.  Some years before, I recollected, he had married Miss Edith Ashmore, whose family was quite prominent socially, and the marriage had attracted a great deal of attention at the time, for she had been a student in one of his courses when he was only an assistant professor.