“Did Billy follow you here?” he asked.  “Perhaps he has a clew.”

“A clew to what?”

“A clew to Potts.  Billy volunteered to work up the Potts case, and I told him to go ahead.”

“Was that fair, Solon, to pit a sleuth as relentless as Billy against poor Potts?”

“All’s fair in love and war.”

“Is it really war?”

“You ask Westley Keyts if he thinks it’s love.”

I think I noticed for the first time then that the Potts affair was etching lines into Solon’s face.

“Of course it’s war,” he went on.  “You know the fix I’m in.  I had the plan to get Potts out.  It was a good plan, too.  The more I think of it the better I like it.  With any man in the world but Potts that plan would have been a stroke of genius.  But I don’t mind telling you that this thing has robbed me of sleep for three months.  Potts has got me talking to myself.  I wake up talking of him, out of the little sleep I do get.  I’ll tell you the fact—­if Potts is here six weeks longer, and let to finish this canvas, my influence in Slocum County is gone.  I might as well give up and move on to another town myself, where my dreadful secret is unknown.”

“Nonsense!  But what can Billy Durgin do?”

“Well, I’m desperate, that’s all.  And one night Billy had me meet him up by the cemetery—­he came disguised in long black whiskers—­and he told me that Potts was James Carruthers, better known to the police of two continents as ‘Smooth Jim,’ wanted for robbing the post-office at Lima, Ohio.  Of course that’s nonsense.  Potts hasn’t the wit to rob a post-office.  But I didn’t have the heart to tell Billy so.  I told him, instead, that this was the chance of his life; to fasten to Potts like an enraged leech, and draw out every secret of his dark past.  You can’t tell—­Billy might find something to pry him into the next county with, anyway.”

“He certainly looked charged with information this afternoon.  He was fizzing like an impatient soda fountain.  But why did he follow me?”

“Well, that might be Billy’s roundabout way of getting to me.  The other time he shadowed Marvin Chislett to get a message to me.  If you’re a detective, you can’t do things the usual way, or all may be lost.”

At that instant a low whistle sounded in our ears, a small missile was thrown over the evergreen hedge, bounding almost to our feet, and a slight but muscular figure was seen retreating swiftly into the dusk.

Solon sprang for the mysterious object.  It was a stone, about which was wrapped a sheet of paper.  This he took off and smoothed out.  By the fading light we made out to read:  “Meet me at graveyard steps at midnight.  You know who.”

We looked at each other.  “Why didn’t he come in here?” I asked.

“That wouldn’t have been detective-like.”

“But the graveyard at midnight!”

“Well, perhaps he won’t hold out for midnight—­Billy is merely poetic at times—­and maybe if we hurry along, we can catch up with him and have it out by the marble works there instead of going clear on to the cemetery.  Perhaps that will be near enough in the right spirit for Billy.”