"Only that we understand it," returned Craig. "I left that geophone down there in the room next door which I hired. I think, if Miss Laidlaw will take us down there, I'd like to get it."
He spoke with a sort of easy confidence which I knew was hard to be assumed in the face of what looked like defeat. Had Craig deliberately let Creighton have a chance to get away, in order that he might convict himself?
In silence, with Miss Laidlaw at the wheel, we went downtown again to the room which Craig had hired next to Creighton's workshop. As we approached it, he leaned over to Miss Laidlaw.
"Stop around the corner," he asked. "Let's go in quietly."
We entered our bare little room and Kennedy set to work as though to detach the geophone, while I explained it to our client.
"What's the matter?" she interrupted in the middle of my explanation, indicating Kennedy.
He had paused and had placed the receivers to his ears. By his expression I knew that the instrument was registering something.
"Someone is in the lower room of the shop next door," he answered, facing us quickly. "If we hurry, we'll have him cornered."
Miss Laidlaw and I went out and around in front, while Craig dashed through a back door to cut off retreat that way.
"What's that? Hurry!" exclaimed Miss Laidlaw.