Mr. Eames, who had made a careful study of Duke Alfred’s reign, came to the conclusion that such excesses were incompatible with the character of a ruler whose love of children was one of his most salient traits.  In regard to those other and vaguer accusations, he contended that the Duke was too jovial by nature to have tortured any save those who, in his opinion, thoroughly deserved it.  Indeed, he was sceptical about the whole thing.  Monsignor Perrelli might have told us the truth, had he cared to do so.  But, for reasons which will appear anon, he is remarkably silent on all that concerns the reign of his great contemporary.  He says nothing more than this: 

“His Highness deigned, during the same year, to restore, and put into its old working order, the decayed heathen rock-chapel vulgarly known as the Cave of Mercury.”

To put into its old working order; that would sound rather suspicious, as though to contain a veiled accusation.  We must remember, however, that the historian of Nepenthe bore a grudge against his Prince (of which likewise more anon), a grudge which he was far too prudent to vent openly; so bitter and personal a grudge that he may have felt himself justified in making a covert innuendo of this kind whenever he could safely risk it.

Meanwhile, everything remained as before—­shrouded in mystery.  Being doubly haunted now, by the Duke’s victims and by those earlier ones, the cave fell into greater neglect than ever.  Simple folk avoided speaking of the place save in a hushed whisper.  It became a proverb among the islanders when speaking of something outrageously improbable:  “Don’t tell me!  Such things only happen in the Cave of Mercury.”  When someone disappeared from his house or hotel without leaving any trace behind—­it happened now and then—­or when anything disreputable happened to anyone, they always said “Try the Cave,” or simply “Try Mercury.”  The path had crumbled away long ago.  Nobody went there, except in broad daylight.  It was as safe a place as you could desire, at night-time, for a murder or a love-affair.  Such was the Cave of Mercury.

Denis had gone to the spot one morning not long after his arrival.  He had climbed down the slippery stairs through that dank couloir or funnel in the rock overhung with drooping maidenhair and ivy and umbrageous carobs.  He had rested on the little platform outside the cavern’s vineyard far below, and upwards, at the narrow ribbon of sky overhead.  Then he had gone within, to examine what was left of the old masonry, the phallic column and other relics of the past.  That was ten days ago.  Now he meant to follow Keith’s advice and go there at midnight.  The moon was full.

“This very night I’ll go,” he thought.