The guard went on, with a nod, and a moment later the signor heard the clangor of a steel door down the corridor as it was closed and locked.  He leaned forward in his chair with half-closed eyes, listening for a long time, then rose and noiselessly approached the cell door.  Again he listened intently, after which he resumed his seat.  He tossed away the cigarette he had and lighted a fresh one, afterward holding the note over the flame of the match.  Here and there, where the paper charred in the heat, a letter or word stood out from the bare whiteness of the paper, and finally, a message complete appeared between the innocuous ink-written lines.  The prisoner read it greedily: 

“Am privately informed there is little chance of Alvarez’s recovery.  Shall I arrange escape for you, or have ambassador intercede?  Would advise former, as the other might take months, and meeting to sign treaty alliance would be dangerously delayed.”

Signor Petrozinni permitted the sputtering flame to ignite the paper, and thoughtfully watched the blaze destroy it.  The last tiny scrap dropped on the floor, burned out, and he crushed the ashes under his heel.  Then he began to write: 

“My Dear Miss Thorne: 

“Many thanks for your courteous little note.  I am delighted to know of the improvement in Senor Alvarez’s condition.  I had hoped that my impulsive act in shooting him would not end in a tragedy.  Please keep me informed of any further change in his condition.  As yet I do not see the necessity of consulting an attorney, but later I may be compelled to do so.

“Respectfully,

“Pietro Petrozinni.”

This done the secret agent carefully cleaned the ink from the pen, wiping it dry with his handkerchief, then thrust it into the half empty glass of milk.  The fluid clung to the steel nib thinly; he went on writing with it, between the lines of ink: 

“I am in no danger.  I hold credentials to United States, which, when presented, will make me responsible only to the Italian government as special envoy, according to international law.  Arrange escape for one week from to-night; use any money necessary.  Make careful arrangements for the test and signing of compact for two nights after.”

Again the prisoner cleaned the steel nib, after which he put it back in the bottle of ink, leaving it there.  He waved the sheet of paper back and forth to dry it, and at last scrutinized it minutely, standing under the light from the high-up window of his cell.  Letter by letter the milk evaporated, leaving the sheet perfectly clean and white except for the ink-written message.  This sheet he folded, placed in an envelope, and addressed.

Later the guard passed along the corridor, and Signor Petrozinni thrust the letter out to him.

“Be good enough to post that, please,” he requested.  “It isn’t sealed.  I don’t know if your prison rules require you to read the letters that go out.  If so, read it, or have it read, then seal it.”