Allen hesitated.
"I did not intend to speak," he murmured; "but for my own sake I must tell you all. When I was coming into Chillum I met a woman going towards Canterbury on a bicycle."
"A woman, Allen! And at midnight--alone! Who was she?"
"At the time I passed her I did not know," said the doctor, rising; "but on my return journey, when I had left the house after the murder, I met her again, by the railway bridge. She was wheeling her machine down the hill, and called out to me to help her. The tyre of her back wheel was punctured. I got off at once, notwithstanding my anxiety to get home, and, with the aid of guttapercha, I soon mended the tiny hole. Then we rode on together until our roads parted."
"Do you know who she was?" asked Dora for a second time.
"Yes," said Allen quietly. "I recognised her at once." He produced a brooch from his waistcoat pocket. "I found this in Edermont's study, where it had no doubt been dropped by her."
"How do you know?"
"By putting two and two together. Look at the brooch."
Dora did so. It was a slender bar of pale gold, to which two letters formed of small pearls were attached. She uttered an exclamation of astonishment as she read them out. "L.B.," she said; "that stands for----"
"For Laura Burville," finished Allen quickly. "Exactly. Laura Burville was the woman I met coming from Chillum. And, by the evidence of the brooch, Laura Burville was the woman who was in Edermont's study on the midnight of the second of August."