Drummond appeared again at the office the next day.  There was no concealment about him now.  He said frankly that he was from the Burr Detective Agency, whose business it was to guard the banks against forgeries.

“The pen work, or, as we detectives call it, the penning,” he remarked, “in the case of that check is especially good.  It shows rare skill.  But the pitfalls in this forgery game are so many that, in avoiding one, a forger, ever so clever, falls into another.”

Carlton felt the polite third degree, as he proceeded:  “Nowadays the forger has science to contend with, too.  The microscope and camera may come in a little too late to be of practical use in preventing the forger from getting his money at first, but they come in very neatly later in catching him.  What the naked eye cannot see in this check they reveal.  Besides, a little iodine vapor brings out the original ‘Green & Co.’ on it.

“We have found out also that the protective coloring was restored by water color.  That was easy.  Where the paper was scratched and the sizing taken off, it has been painted with a resinous substance to restore the glaze, to the eye.  Well, a little alcohol takes that off, too.  Oh, the amateur forger may be the most dangerous kind, because the professional regularly follows the same line, leaves tracks, has associates, but,” he concluded impressively, “all are caught sooner or later—­sooner or later.”

Dunlap managed to maintain his outward composure admirably.  Still the little lifting of the curtain on the hidden mysteries of the new detective art produced its effect.  They were getting closer, and Dunlap knew it, as Drummond intended he should.  And, as in every crisis, he turned naturally to Constance.  Never had she meant so much to him as now.

That night as he entered the apartment he happened to glance behind him.  In the shadow down the street a man dodged quickly behind a tree.  The thing gave him a start.  He was being watched.

“There is just one thing left,” he cried excitedly as he hurried upstairs with the news.  “We must both disappear this time.”

Constance took it very calmly.  “But we must not go together,” she added quickly, her fertile mind, as ever, hitting directly on a plan of action.  “If we separate, they will be less likely to trace us, for they will never think we would do that.”

It was evident that the words were being forced out by the conflict of common sense and deep emotion.  “Perhaps it will be best for you to stick to your original idea of going west.  I shall go to one of the winter resorts.  We shall communicate only through the personal column of the Star.  Sign yourself Weston.  I shall sign Easton.”

The words fell on Carlton with his new and deeper love for her like a death sentence.  It had never entered his mind that they were to be separated now.  Dissolve their partnership in crime?  To him it seemed as if they had just begun to live since that night when they had at last understood each other.  And it had come to this—­separation.