at her niece with the compelling look of a Fate, but the girl stood firm. Gently she freed herself from the clinging arm and sat, or rather fell, into the big cushioned chair once more. Her aunt hesitated for a moment, I could see, whether or not to use force, but decided against the attempt. With a level gaze of scorn for me, she took her stand beside Grace's chair, her hand clenched on the carving of its high back. I realised the tension of her grip, because her grey suede glove split open across a curious ring she always wore on the third finger of her left hand, showing its great cabochon emerald. I had often noticed this stone, and thought it like the eye of a snake.
"Say what you wish to say quickly, then, and get it over," she sharply ordered.
"The double murder was suggested and carried out by a man, but he had accomplices, and his principal accomplice was a woman." (Miss Callender's command excused my brusqueness.) "They had the same interest to serve; purely a financial interest. It was vital to both that Miss Grace Callender shouldn't marry – unless she married a person under their influence who would share with them. They preferred some such scheme, but it fell through. That drove them to extremes. Now I'll tell you something about this couple – this congenial husband and wife. Afterwards I'll give you details of their plot. They were married secretly years ago, and lived together when they could, abroad and on this side. The man was rich once, but lost his money – and the capacity to make it – by losing his health. Life wasn't worth living to either unless they could have the luxury they'd been used to. They took an old house on Long Island – Bay View Farm, near Sandy Plain. The man lived there for several months each year under the name of Paulling. His wife paid him flying visits. She provided the money, and had a banking account in the town. At Bay View Farm, when Miss Grace first engaged herself to her cousin, the two thought out their plot to suppress Perry. It took them some time to elaborate it, but a week before the wedding they were ready. The woman, still under the name of Paulling, engaged a furnished flat in New York, near Riverside Drive. She took this flat for a term of years, realising it might be needed more than once as time went on. In this apartment, in a house called the Alhambra, she sat down one day at her desk and wrote an anonymous letter to Perry Callender-Graham. She asked him to call at that address at midnight the next night and learn a secret concerning his cousin Grace's birth, which would change everything for them both if it came out. Her handwriting was disguised by the use of a quill pen, which used so much ink that most of the words left traces on the blotter. The envelope and paper were blue-grey, and thick. Inside was enclosed a small latchkey and a key to the front door of the house, for the hall-porter would be in bed by the time she named. Perry Callender-Graham could not resist the temptation to keep the appointment. He went to the Alhambra, let himself in, was seen by nobody, walked up to the third floor, and fitted the latchkey into the door on the right side of the hall. As he tried to turn the key something sharp as a needle pricked his forefinger. He was startled, yet he went on trying to unlock the door. The key turned all the way round, but the door stuck. It seemed to be bolted on the inside. He began to feel slightly faint, but he was so angry at being cheated that he pushed the electric bell, determined to get in at any cost. No answer came, however, and at last he gave up in despair. Some vague idea of warning the police and of going to see a doctor came to his mind, but he was already a dying man. Before he got as far as the street corner he fell dead. Exactly the same thing happened in the case of Ned, when every effort to frighten him into breaking his engagement had failed, when his love for his brother, his sensitive conscience and his superstitious fear had all been played upon in vain. Even the same formula was used for the anonymous letter, with a slightly different wording. That was safe enough, for if Perry had mentioned the first letter to Ned he would have told the police at the time of Perry's death; it would have been a valuable clue. It wasn't necessary to make new keys, for the two originals had been returned – 'to the family.' They were sent anonymously to Ned as they'd been sent to Perry, and he also yielded to curiosity.
"The same ingenious lock, made for the plotters by a skilled mechanician (whom they had reason to trust), shot out its poisoned needle at the first turn of the latchkey in his hand. As for the poison, it, too, was supplied by a trusted one – one who had something to gain and vengeance to take as well. As the mechanician specialised in lock-making, so did the chemist employed specialise in poisons. The one he chose out of his repertory had two virtues: first, it began to stop the heart's action only after coursing through the blood for twenty or thirty minutes. Anything quicker might have struck down the victim in front of the door and put the police on the right track. Secondly, the poison's effect on the heart couldn't be detected by post-mortem, but presented all the symptoms of status lymphaticus, enlargement of the thyroid gland and so on. As for the lock, the second turn of the key caused the needle to retire; and for a further safeguard, an almost invisible stop, resembling a small screw-head, could hold the needle permanently in place inside the lock, so that the door might be opened by a latchkey and the existence of a secret mechanism never suspected, except by one who knew how to find it. The mechanism is in working order still, ready for use again, in case Miss Grace Callender should change her mind and decide to marry."
"Who is it you are accusing, Lord John?" Grace stammered in a choked voice.
I glanced from the drooping figure in the chair to the tall figure standing erect and straight beside it. Marian Callender no longer grasped the oak carving. The hand in the ragged glove was crushed against her mouth, her lips on the emerald which had pressed through the torn suede. The woman gave no other sign of emotion than this strange gesture.
"I accuse Paolo Tostini, with his father, his brother, and his wife – known still as Miss Marian Callender – as his accomplices," I said.
Grace uttered a cry sharp with horror, yet there was neither amazement nor unbelief in the pale face which she screened with two trembling hands. The story I had told – hastily yet circumstantially – had prepared her for the end. But the keen anguish in the girl's voice snapped the last strand of Odell's patience. He threw the iron door of the safe wide open, and in two bounds was at Grace's side. I saw her hold out both arms to him. I saw him snatch her up against his breast; and then I turned to Marian Tostini, who had not moved from her place beside the big carved chair. She was staring straight at me, her dark eyes wide and unwinking as the eyes of a person hypnotised. The hand in the torn glove had dropped from her lips again and clasped the carving. She seemed to lean upon the chair, as if for support. Her fingers clutched the wood. The grey suede glove was slit now all across its back, but the snake-eye of the emerald had ceased to shoot out its green glint. The stone hung from its setting like the hinged lid of a box, showing a very small gold-lined aperture.
"There need be – no stain on the name of – Callender – if you are as clever in hiding the secret as you've been – in finding it out," she said, with a catch in her breath between words.
"What have you done?" I asked.
"You know – don't you – you who know everything? The ring was my Italian mother's – and her mother's before her. Who can tell how long it has been in our family? It was empty when it came to me, but – "
"But you put into it some of the same poison Antonio Tostini made up for Perry and Ned Callender-Graham?"
"Do you think you can force me to accuse the Tostinis? You shall not drag a word from me. When Paolo hears I am dead he will die also, before you can find him. Antonio you cannot touch. He is in Italy. Thank Heaven their father is dead! And now I think – I had better go home or – or to my doctor's. Grace and Roger Odell – wouldn't like me to die here. It might – start scandal. I am feeling – a little faint."
"Aunt Marian!" Grace sobbed. But Odell held the girl in his arms and would not let her go.
"Take Miss Callender away, Odell – quickly," I advised. "I'll attend to – Mrs. Tostini."
Like one who walks in a dream I shut the safe on my way to the desk, and telephoned downstairs for a taxi. "One of the ladies who called has been taken ill, I must drive her to a doctor's," I explained.
"You think
