I want to formulate a plan first." "Who are we," the Professor asked drearily, "to make plans against a fiend like that?
What can we do against men who have revolving staircases and trolley-loads of river pirates waiting for them?
You may be a scientific criminologist, Quest, but that fellow Craig is a scientific criminal, if ever there was one." Quest crossed the room towards his cigar cabinet, and opened it.

His little start was apparent to both of them.

Lenora laid down the bag which she had just lifted up.

The Professor leaned forward in his chair.
"What is it, Quest ?" he demanded.
Quest stretched out his hand and picked up from the top of the cigars a small black box! He laid it on the table.
"Unless I am very much mistaken," he said, "it is another communication from our mysterious friend." "Impossible!" the Professor exclaimed hoarsely.
"How can he have been here ?" Lenora cried.
Quest removed the lid from the box and drew out a circular card.

Around the outside edge was a very clever pen and ink sketch of a lifebuoy, and inside the margin were several sentences of clear handwriting.