"Is it certain that they went there?"

"Two C.I.D. men, who were shadowing, actually saw the pair of them enter. A signal had been arranged, but it was never given; and at about half-past four the place was raided."

"Surely some arrests were made?"

"But there was no evidence!" cried Ryman. "Every inch of the rat-burrow was searched. The Chinese gentleman who posed as the proprietor of what he claimed to be a respectable lodging-house, offered every facility to the police. What could we do?"

"I take it that the place is being watched?"

"Certainly," said Ryman. "Both from the river and from the shore. Oh! they are not there! God knows where they are, but they are not there!"

I stood for a moment in silence, endeavouring to determine my course; then, telling Ryman that I hoped to see him later, I walked out slowly into the rain and mist, and nodding to the taxi-driver to proceed to our original destination, I re-entered the cab.

As we moved off, the lights of the River Police depôt were swallowed up in the humid murk, and again I found myself being carried through the darkness of those narrow streets, which, like a maze, hold secret within their Labyrinth mysteries great, and at least as foul, as that of Parsiphaë.

The marketing centres I had left far behind me; to my right stretched the broken range of riverside buildings, and beyond them flowed the Thames, a stream heavily burdened with secrets as ever were Tiber or Tigris. On my left, occasional flickering lights broke through the mist, for the most part the lights of taverns; and saving these rents in the veil, the darkness was punctuated with nothing but the faint and yellow luminance of the street lamps.

Ahead was a black mouth, which promised to swallow me up as it had swallowed up my friend.