“Did your employer do anything with radio-active work?”

“Yes, sir. He died that way. He was killed, paralysed, you might say, while working with something in a locked room. He always did that work in a locked room.”

“What were the circumstances of his death?” asked Tom. The man hesitated and looked up somewhat fearfully.

“I don’t see what that has to do with phosphorescent ink,” he said. “The police went all into the matter of his death, and they said it was just death by paralysis.” He stopped and shut his mouth hard. Dorothy broke in.

“Mr. Swenton, here is the state of affairs. I don’t think my brother has made it quite plain. We are more interested in Dr. Heidenmuller’s radio-active work than in his phosphorescent paint. We have no question of you at all. We do not want to know anything which is not entirely right for us to know, but we do want to know all you feel you can rightly tell us of his work. I feel sure that my brother will be ready to employ you, if you can show that you have done this, and that you can do what he wants.”

The man’s face cleared. Dorothy’s words were more convincing than evidence. He reached into his pockets and drew forth a bunch of papers, which he gave to Tom, who rapidly ran through them.

“They’re all right,” he said, handing them back. “Now, if I give you twenty pounds a month for two months, will that be all right?”

A dull red rose in the man’s face as his eyes lighted. “It will mean everything to me, sir,” he said. “I’ve got a wife and a boy.”

Tom drew out his purse. “Here’s ten pounds to clinch the bargain,” and he handed him two five pound notes.