library he deposited Limpy's document in an envelope containing
all the correspondence that had lead up to the final step in the
discovery.

. . . . . . . .

It was late in the evening when I returned to our apartment and,
not finding Kennedy there, knew that I would discover him at the
laboratory.

"Craig," I cried as I burst in on him, "I've got a case for you--
greater than any ever before!"

Kennedy looked up calmly from the rack of scientific instruments
that surrounded him, test tubes, beakers, carefully labelled
bottles.

He had been examining a piece of cloth and had laid it aside in
disappointment near his magnifying glass. Just now he was watching
a reaction in a series of test tubes standing on his table. He was
looking dejectedly at the floor as I came in.

"Indeed?" he remarked coolly going back to the reaction.

"Yes," I cried. "It is a scientific criminal who seems to leave no
clues."

Kennedy looked up gravely. "Every criminal leaves a trace," he
said quietly. "If it hasn't been found, then it must be because no
one has ever looked for it in the right way."