“His precautions here have baffled the enemy, I think.  The attempt in the train points to an anxiety to waste no opportunity.  But whilst Eltham was absent (he was getting his outfit in London, by the way) they have been fixing some second string to their fiddle here.  In case no opportunity offered before he returned, they provided for getting at him here!”

“But how, Smith?”

“That’s the mystery.  But the dead dog in the shrubbery is significant.”

“Do you think some emissary of Fu-Manchu is actually inside the moat?”

“It’s impossible, Petrie.  You are thinking of secret passages, and so forth.  There are none.  Eltham has measured up every foot of the place.  There isn’t a rathole left unaccounted for; and as for a tunnel under the moat, the house stands on a solid mass of Roman masonry, a former camp of Hadrian’s time.  I have seen a very old plan of the Round Moat Priory as it was called.  There is no entrance and no exit save by the steps.  So how was the dog killed?”

I knocked out my pipe on a bar of the grate.

“We are in the thick of it here,” I said.

“We are always in the thick of it,” replied Smith.  “Our danger is no greater in Norfolk than in London.  But what do they want to do?  That man in the train with the case of instruments—­what instruments?  Then the apparition of the green eyes to-night.  Can they have been the eyes of Fu-Manchu?  Is some peculiarly unique outrage contemplated—­ something calling for the presence of the master?”

“He may have to prevent Eltham’s leaving England without killing him.”

“Quite so.  He probably has instructions to be merciful. 
But God help the victim of Chinese mercy!”

I went to my own room then.  But I did not even undress, refilling my pipe and seating myself at the open window.  Having looked upon the awful Chinese doctor, the memory of his face, with its filmed green eyes, could never leave me.  The idea that he might be near at that moment was a poor narcotic.

The howling and baying of the mastiff was almost continuous.

When all else in Redmoat was still the dog’s mournful note yet rose on the night with something menacing in it.  I sat looking out across the sloping turf to where the shrubbery showed as a black island in a green sea.  The moon swam in a cloudless sky, and the air was warm and fragrant with country scents.

It was in the shrubbery that Denby’s collie had met his mysterious death—­ that the thing seen by Miss Eltham had disappeared.  What uncanny secret did it hold?

Caesar became silent.

As the stopping of a clock will sometimes awaken a sleeper, the abrupt cessation of that distant howling, to which I had grown accustomed, now recalled me from a world of gloomy imaginings.

I glanced at my watch in the moonlight.  It was twelve minutes past midnight.

As I replaced it the dog suddenly burst out afresh, but now in a tone of sheer anger.  He was alternately howling and snarling in a way that sounded new to me.  The crashes, as he leapt to the end of his chain, shook the building in which he was confined.  It was as I stood up to lean from the window and commanded a view of the corner of the house that he broke loose.