have been the place where Pedley was drowned.” “The duck-weed in this ditch is, of course, the Greater Duck-weed?” “Yes. I have taken some specimens as well as the horn-weed and shells.” He opened the vasculum and picked out one of the tiny plants, exhibiting the characteristic tassel of roots. “I shall write to Parton and tell him to preserve the jar and the horn-weed if it has not been thrown away. But the duck-weed alone, produced in evidence, would be proof enough that Pedley was not drowned in the Bantree ditch; and the dental plate will show where he was drowned.” “Are you going to pursue the case any farther?” I asked. “No,” he replied. “I shall call at Scotland Yard on my way home and report what I have learned and what I can prove in court. Then I shall have finished with the case. The rest is for the police, and I imagine they won’t have much difficulty. The circumstances seem to tell their own story. Pedley was employed by the Foreign Office, probably on some kind of secret service. I imagine that he discovered the existence of a gang of evil-doers--probably foreign revolutionaries, of whom we may assume that our friend the manager of the factory is one; that he contrived to associate himself with them and to visit the factory occasionally to ascertain what was made there besides Golomite--if Golomite is not itself an illicit product. Then I assume that he was discovered to be a spy, that he was lured down here; that he was pinioned and drowned some time on Tuesday night and his body put into the van and conveyed to a place miles away from the scene of his death, where it was deposited in a ditch apparently identical in character with that in which he was drowned. It was an extremely ingenious and well-thought-out plan. It seemed to have provided for every kind of inquiry, and it very narrowly missed being successful.” “Yes,” I agreed. “But it didn’t provide for Dr. John Thorndyke.” “It didn’t provide for a searching examination of all the details,” he replied; “and no criminal plan that I have ever met has done so. The completeness of the scheme is limited by the knowledge of the schemers, and, in practice, there is always something overlooked. In this case, the criminals were unlearned in the natural history of ditches.” Thorndyke’s theory of the crime turned out to be substantially correct. The Golomite Works proved to be a factory where high explosives were made by a gang of cosmopolitan revolutionaries who were all known to the police. But the work of the latter was simplified by a detailed report which the dead man had deposited at his bank and which was discovered in time to enable the police to raid the factory and secure the whole gang. When once they were under lock and key, further information was forthcoming; for a charge of murder against them jointly soon produced King’s Evidence sufficient to procure a conviction of the three actual perpetrators of the murder. V. MR. PONTING’S ALIBI