Silently the six men waited.

A few minutes later Miss Crayne entered, pale but self-possessed.

She closed the door behind her. Suddenly she caught sight of the curate. Her eyes widened, and her paleness seemed to become accentuated. A moment later it was followed by a crimson flush. She hesitated, her hands clenched at her side, then with a manifest effort she appeared to control herself and, with a slight smile and inclination of her head, took the chair the schoolmaster moved towards her. Instinctively she turned her eyes toward Malcolm Sage.

"Inspector Murdy," he said, without raising his eyes, "will you please open two of those packets?" He indicated the pile upon his left. "I should explain," he continued, "that each of these contains one of the most recent of the series of letters with which we are concerned. Each was sealed up by Mr. Crayne immediately it reached him, in accordance with Inspector Murdy's request. Therefore, only the writer, the recipient and the vicar have had access to these letters."

Malcolm Sage turned his eyes interrogatingly upon Mr. Crayne, who bowed.

Meanwhile the inspector had cut open the two top envelopes, unfolded the sheets of paper they contained, and handed them to Malcolm Sage.

All eyes were fixed upon his long, shapely fingers as he smoothed out one of the sheets of paper upon the vicar's blotting-pad. Then, lifting the steel plate by the handle, he placed it upon the upturned sheet of paper.

The tension was almost unendurable. The heavy breathing of Inspector Murdy seemed like the blowing of a grampus. Mr. Gray glanced across at him irritably. The vicar coughed slightly, then looked startled that he had made so much noise.

Everyone bent forward, eagerly expecting something; yet without quite knowing what. Malcolm Sage lifted the metal plate from the letter. There in the centre of the page, in bluish-coloured letters, which had not been there when the paper was smoothed out upon the blotting-pad, appeared the words:----

Malcolm Sage, August 12th, 1919.

No. 138.

For some moments they all gazed at the paper as if the mysterious blue letters exercised upon them some hypnotic influence.

"Secret ink!"

It was Robert Freynes who spoke. Accustomed as he was to dramatic moments, he was conscious of a strange dryness at the back of his throat, and a consequent huskiness of voice.

His remark seemed to break the spell. Instinctively everyone turned to him. The significance of the bluish-coloured characters was slowly dawning upon the inspector; but the others still seemed puzzled to account for their presence.

Immediately he had lifted the plate from the letter, Malcolm Sage had drawn a sheet of plain sermon paper from the rack before him.

This he subjected to the same treatment as the letter. When a few seconds later he exposed it, there in the centre appeared the same words:----

Malcolm Sage, August 12th, 1919.

but on this sheet the number was 203.

Then the true significance of the two sheets of paper seemed to dawn upon the onlookers.

Suddenly there was a scream, and Muriel Crayne fell forward on to the floor.

"Oh! father, father, forgive me!" she cried, and the next moment she was beating the floor with her hands in violent hysterics.

III

"From the first I suspected the truth," remarked Malcolm Sage, as he, Robert Freynes and Inspector Murdy sat smoking in the car that Tims was taking back to London at its best pace. "Eighty-five years ago a somewhat similar case occurred in France, that of Marie de Morel, when an innocent man was sentenced to ten years' imprisonment, and actually served eight before the truth was discovered."

The inspector whistled under his breath.

"This suspicion was strengthened by the lengthy account of the affair written by Miss Crayne, which Murdy obtained from her. The punctuation, the phrasing, the inaccurate use of auxiliary verbs, were identical with that of the anonymous letters.

"Another point was that the similarity of the handwriting of the anonymous letters to Blade's became more p.r.o.nounced as the letters themselves multiplied. The writer was becoming more expert as an imitator."

Freynes nodded his head several times.

"The difficulty, however, was to prove it," continued Malcolm Sage.

"There was only one way; to subst.i.tute secretly marked paper for that in use at the vicarage.

"I accordingly went down to Gylston, and the vicar found me keenly interested in monumental bra.s.ses, his pet subject, and Norman architecture. He invited me to the vicarage. In his absence from his study I subst.i.tuted a supply of marked Olympic Script in place of that in his letter-rack, and also in the drawer of his writing-table.

As a further precaution, I arranged for my fountain-pen to run out of ink. He kindly supplied me with a bottle, obviously belonging to his daughter. I replenished my pen, which was full of a chemical that would enable me, if necessary, to identify any letter in the writing of which it had been used. When I placed my pen, which is a self-filler, in the ink, I forced this liquid into the bottle."

The inspector merely stared. Words had forsaken him for the moment.

"It was then necessary to wait until the ink in Miss Crayne's pen had become exhausted, and she had to replenish her supply of paper from her father's study. After that discovery was inevitable."

"But suppose she had denied it?" questioned the inspector.

"There was the ink which she alone used, and which I could identify," was the reply.

"Why did you ask Gray to be present?" enquired Freynes.

"As his name had been a.s.sociated with the scandal it seemed only fair," remarked Malcolm Sage, then turning to Inspector Murdy he said, "I shall leave it to you, Murdy, to see that a proper confession is obtained. The case has had such publicity that Mr.

Blade's innocence must be made equally public."

"You may trust me, Mr. Sage," said the inspector. "But why did the curate refuse to say anything?"

"Because he is a high-minded and chivalrous gentleman," was the quiet reply.

"He knew?" cried Freynes.

"Obviously," said Malcolm Sage. "It is the only explanation of his silence. I taxed him with it after the girl had been taken away, and he acknowledged that his suspicions amounted almost to certainty."

"Yet he stayed behind," murmured the inspector with the air of a man who does not understand. "I wonder why?"

"To minister to the afflicted, Murdy," said Malcolm Sage. "That is the mission of the Church."

"I suppose you meant that French case when you referred to the 'master-key,'" remarked the inspector, as if to change the subject.

Malcolm Sage nodded.

"But how do you account for Miss Crayne writing such letters about herself?" enquired the inspector, with a puzzled expression in his eyes. "Pretty funny letters some of them for a parson's daughter."

"I'm not a pathologist, Murdy," remarked Malcolm Sage drily, "but when you try to suppress hysteria in a young girl by sternness, it's about as effectual as putting ointment on a plague-spot."

"s.e.x-repression?" queried Freynes.

Malcolm Sage shrugged his shoulders; then after a pause, during which he lighted the pipe he had just re-filled, he added: