We received the volley of misplaced aspirates with joyous hearts, noting the gleam of avid curiosity in the watery eyes, as the clerk thought of the mysterious laboratory on the top floor. All he could tell was that the top floor had been let a few months before to a tall man. With the usual vagueness of his type of mind, that was as far as he could go. Over and over again he repeated the same indefinite phrase, a tall man. When the man moved in, a couple of vans had brought strange furnishings, a small furnace, glassware and instrument cases. A little while ago an assistant had appeared, a foreigner who knew no English, or at least refused to understand the language. The two, the man and his assistant, often worked together till late at night. Sometimes, the clerk believed, they worked all night. As for him, he would have repeated the thing to the police. He didn’t believe in having mysteries like that around, but his master, the proprietor of the book shop, refused to part with regular paying tenants. Yes, sir, he’d tried again and again to see what they were doing, but there was a curtain over the door, and you couldn’t see anything through the keyhole. The door was always locked, so that the adventurous spirit of the clerk had to be content with imagining the horrible crimes perpetrated behind the curtained door. This certainly looked good. With anxious hearts, Tom and I started up the stairs in search once more of our Cousin George, halting, however, at the second story, once the clerk was left safely behind. “It certainly looks like queer street, anyway,” remarked Tom reflectively. “It may be the man, or it may be some bunch of counterfeiters or other criminals. I’m not going to back down for a minute, but I think one of us had better hunt up Dorothy, tell her where we are, and have her put the police on the trail, if we shouldn’t happen to turn up to-night. Strikes me that that would be only an elementary precaution.” “I’ll do it,” I said. “You watch here.” Before Tom could object, I was half way down the stairs and out on the street. On Tottenham Court Road, I found Dorothy driving up and down. She leaned forward questioningly as I jumped in. I nodded in answer, “Yes. We’ve got the place, but we need your help now.” Warned by experience as to its necessity, I had mapped out my line of argument carefully, as I hurried along. “We have the very place, but we want you to stay outside and send us help, if we should get into trouble.” Dorothy’s face fell. “I want to go with you the worst way,” she said. “Yet I don’t like the idea of you two going into danger without any outside assistance. What have you found out?”