"I don't know," Hester answered. "All we can do is find out what happened to Mary . . . maybe. If she found proof of some sort-I mean something that would have shut down the works until the machines were made safe, even if it were slower-whom would she have told?"

"Morgan," Rose said straightaway. "She didn't. She never came back."

They started walking again, as it was too cold to stand.

"Perhaps she wasn't certain," Hester suggested. "If it was almost complete, perhaps lacking one point... ?"

They reached the bus stop and stood side by side, moving their weight from one foot to the other to prevent themselves from freezing.

"Toby?" Hester pressed. "She might have told him?"

Rose shook her head. "She didn't trust him. He and Alan were very close."

"Toby worked in the company?"

"Yes. She said he was very ambitious, and at least as clever as Alan, with engineering, at any rate. Perhaps not as good at handling men and as quick in business."

Half an idea flashed into Hester's mind, but it dissolved before she grasped hold of it. "So he would understand the machines?"

"Oh, yes. So others said." Rose's eyes widened. "You mean she might have been ... been deliberately playing him ... drawing information from him to get her final proof?"

"Mightn't she?" Hester asked. "Would she have had the courage to do that?"

Rose did not hesitate. "Yes-by heaven, she would! And he was playing her, to see how much she knew! But it was too much! He had to kill her, because in the end his loyalty was to his brother."

"And to his own ambition," Hester retorted. She saw lights along the road and prayed it was the omnibus at last. Her teeth were chattering with the cold.

"How will we ever know?" Rose said desperately. "I absolutely refuse to let them get away with it, whatever it costs!"

The omnibus stopped and they climbed on, being obliged to stand jammed between tired workmen and women with bags of shopping followed by exhausted children with loud voices and sticky hands.

At the changeover to the second omnibus Rose gave a wry, blisteringly honest smile as she climbed onto the next platform and inside. "I shall never be rude to a coachman again!" she whispered fiercely. "I shall never insult the cook, outrage the maids, or argue with the butler. And above all, I shall never let the fire go out, even if I have to carry the coal in myself!"

Hester swallowed a laugh that was a little on the edge of hysteria.

"What are we going to do?" Rose demanded.