“How oft the sight of means to do ill deeds makes ill deeds done.”

The master of human nature had anticipated the excuse of many King Johns. And in this case the excuse seemed genuine. In fact, the widow did not speak as though she meant to excuse herself; she seemed to be simply explaining the sequence of her thoughts.

“Then I came to a new difficulty, that I had never expected. I found I couldn’t do it.”

It sounded like confession. There was far more of apology in the tone with which she said this than there had been in her whole previous statement. For the first time there was moisture in her eyes.

“I had believed in him once.... I had loved him.”

She broke down and ceased for a few moments. Tarleton watched her with real pity.

“I dare say you will find it difficult to understand me, Sir Frank, but I think most wives would. I hadn’t changed my mind. I was still quite firm in believing that it was right to put an end to my husband, but I had to find someone else to do it.”

The consultant nodded. It was all plain to him now. His theory had not been very far wrong, after all.

“I decided that I must try to discover one of his victims, one of the men who had confessed their secrets to him and were suffering in consequence, and give the poison to him. I didn’t think of the appointment-book, unfortunately. The only way that occurred to me of getting in touch with the writers of the letters was to go to the Domino Club.”

Tarleton felt astray again for the moment. There were more complications in the case than he had even yet grasped.