"On some undiscovered incident in Sir Marcus's past, beyond a doubt.

Probably an amorous adventure."

"You're wrong," said Gatton grimly. "It turns on the figure of the green cat. Good-by. Five o'clock."

CHAPTER V

THE INTERRUPTED SUPPER

I arrived at the Red House before Inspector Gatton. A constable was on duty at the gate and as I came up and paused he regarded me rather doubtfully until I told him that I had an appointment with Gatton. I stared up the drive towards the house. It was not, apparently, a very old building, presenting some of the worst features of the mid-Victorian period, and from whence it derived its name I could not conjecture unless from the fact that the greater part of the facade was overgrown with some kind of red creeper.

The half-moon formed by the crescent-shaped carriage-way and the wall bordering the road was filled with rather unkempt shrubbery, laurels and rhododendrons for the most part, from amid which arose several big trees. In the blaze of the afternoon sun the place looked commonplace enough with estate agents' bills pasted in the dirty windows, and it was difficult to conceive that it had been the scene of the mysterious crime of which at that hour all London was talking and which later was to form a subject of debate throughout the civilized world.

Gatton joined me within a few minutes of my arrival. He was accompanied by Constable Bolton with whom I had first visited the Red House. Bolton was now in plain clothes, and he had that fish-out-of-water appearance which characterizes the constable in mufti. Indeed he looked rather dazed, and on arriving before the house he removed his bowler and mopped his red face with a large handkerchief, nodding to me as he did so.

"Good afternoon, sir; it was lucky you came along with me last night.

I thought it was a funny go and I was right, it seems."

"Quite right," said Gatton shortly, "and now here are the keys which you returned to the depot this morning."

From his pocket the Inspector produced a steel ring bearing a large and a small key which I recognized as that which had hung from the lock of the garage door on the previous night.

We walked along to the garage and Inspector Gatton placed the key in the lock; then turning to Bolton:

"Now," he directed, "show us exactly what you did."

Bolton replaced his bowler, which hitherto he had carried in his hand, hesitated for a moment, and then unlocked the door.

"Of course I had my lantern with me last night," he explained, "and this gentleman and myself stood looking in for a moment."

"Mr. Addison has already described to me exactly what he saw," said Gatton. "Show us what you did after Mr. Addison left you."

Bolton, with a far-away look in his eyes betokening an effort of retrospection, withdrew the key from the lock and entered the garage, Gatton and I following. There was a sky window to light the place, so that when Bolton reclosed the door we could see well enough. His movements were as follows: Relocking the door from the inside, he walked slowly along to a smaller door at the opposite end and with the other key attached to the ring unfastened it.

"Wait a moment," said Gatton. "Did you look about you at all before opening this door?"

"Only long enough to find where it was, sir. Just about as long as I showed you."

"All right. Go on, then."

We followed Bolton out into a very narrow hedge-bordered path, evidently a tradesman's entrance, and he turned and locked the door behind him. Slipping the keys into his pocket, he tramped stolidly out to the main road whereon we emerged immediately beside the garage.

"Ah," murmured Gatton. "Now give me the keys," and as the man did so: "Throughout all this time did you see or hear anything of an unusual nature?"

Bolton removed his bowler once more. I had gathered by this time that he regarded fresh air as an aid to reflection.

"Well, sir," he replied in a puzzled way, "that first door--"

"Well," said Gatton, as the man hesitated.

"It seemed to open more easily just now than it did last night. There seemed to be a sort of hitch before when it was about half-way open."

"Perhaps the crate was in the way?" suggested Gatton. "Except for the absence of the crate do you notice anything different, anything missing, or anything there now that was not there before?"

Bolton shook his head.

"No," he answered; "it looks just the same to me--except, as I say, that the door seemed to open more easily."

"H'm," muttered Gatton; "and you carried the keys in your pocket until you went off duty?"

"Yes, sir."

"All right. You can go now."

Bolton touched his bowler and departed, and Gatton turned to me with a grim smile.

"We'll just step inside again," he said, "so as not to attract any undue attention."

He again unlocked the garage door and closed it as we entered.

"Now," said he, "before we go any further what was your idea in keeping back the fact that one of the missing links in the chain of evidence was already in your possession?"

"No doubt," I said rather guiltily, "you refer to the fact of my acquaintance with Miss Isobel Merlin?"

"I do!" said Gatton, "and to the fact that you nipped in ahead of me and interviewed this important witness before I had even heard of her existence." He continued to smile, but the thoroughness and unflinching pursuit of duty which were the outstanding features of the man, underlay his tone of badinage. "I want to say," he continued, "that for your cooperation, which has been very useful to me on many occasions, I am always grateful, but if in return I give you facilities which no other pressman has, I don't expect you to abuse them."

"Really, Inspector," I replied, "you go almost too far. I have done nothing to prejudice your case nor could I possibly have known until my interview this morning with Miss Merlin, that it was she in whom the late Sir Marcus was interested."

"H'm," said Gatton, but still rather dubiously, his frank, wide-open eyes regarding me in that nave manner which was so deceptive.

"All that I learned," I continued, "is unequivocally at your disposal.

Finally I may tell you--and I would confess it to few men--that Miss Merlin is a very old friend and might have been something more if I had not been a fool."

"Oh!" said Gatton, and his expression underwent a subtle change--"Oh!

That's rather awkward; in fact"--he frowned perplexedly--"it's d.a.m.ned awkward!"

"What do you mean?" I demanded.

"Well," said he, "I don't know what account Miss Merlin gave to you of her relations with Sir Marcus--"

"Relations!" I said hotly, "the man was a mere acquaintance; she hadn't even seen him, except from the stage, for some months past."

"Oh," replied Gatton, "is that so?" He looked at me very queerly. "It doesn't seem to dovetail with the evidence of the stage-doorkeeper."

I felt myself changing color, and: