One day he called Dunn up to admire a problem he had just composed.

“Pretty clever, eh?” he said, admiring his own work with much complacence.  “Quite an original idea of mine and I think the key move will take some finding.  What do you say?  I suppose you do play chess?”

“Only a very little,” answered Dunn.

“Try a game with me,” said Deede Dawson, and won it easily, for in fact, Dunn was by no means a strong player.

His swift victory appeared to delight Deede Dawson immensely.

“A very pretty mate I brought off there against you,” he declared.  “I’ve not often seen a prettier.  Now you try to solve that problem of mine, it’s easy enough once you hit on the key move.”

Dunn thought to himself that there were other and more important problems which would soon be solved if only the key move could be discovered.

He said aloud that he would try what he could do, and Deede Dawson promised him half a sovereign if he solved it within a week.

“I mayn’t manage it within a week,” said Dunn.  “I don’t say I will.  But sooner or later I shall find it out.”

During all this time he had seen little of Ella, who appeared to come very little into the garden and who, when she did so, avoided him in a somewhat marked manner.

Her mother, Mrs. Dawson, was a little faded woman, with timid eyes and a frightened manner.  Her health did not seem to be good, and Ella looked after her very assiduously.  That she went in deadly fear of her husband was fairly evident, though he seemed to treat her always with great consideration and kindness and even with a show of affection, to which at times she responded and from which at other times she appeared to shrink with inexplicable terror.

“She doesn’t know,” Dunn said to himself.  “But she suspects —­something.”

Ella, he still watched with the same care and secrecy, and sometimes he seemed to see her walking amidst the flowers as an angel of sweetness and laughing innocence; and sometimes he saw her, as it were, with the shadow of death around her beauty, and behind her gentle eyes and winning ways a great and horrible abyss.

Of one thing he was certain—­her mind was troubled and she was not at ease; and it was plain, also, that she feared her smiling soft-spoken stepfather.

As the days passed, too, Dunn grew convinced that she was watching him all the time, even when she seemed most indifferent, as closely and as intently as he watched her.

“All watching together,” Dunn thought grimly.  “It would be simple enough, I suppose, if one could hit on the key move, but that I suppose no one knows but Deede Dawson himself.  One thing, he can’t very well be up to any fresh mischief while he’s lounging about here like this.  I suppose he is simply waiting his time.”

As for the chess problem, that baffled him entirely.  He said as much to Deede Dawson, who was very pleased, but would not tell him what the solution was.