“As he practically admitted to me, that he had come for a letter written on slatey-blue official-looking paper.” The girl held up the letter from Rotterdam. “All this,” the girl continued, “made me think that this letter must have had something to do with Hartley’s death ...” “Surely an additional reason for giving it to the police!...” Mary Trevert set her mouth in an obstinate line. “No!” she affirmed uncompromisingly. “The police believe that, as the result of a scene between Hartley and Robin, Hartley killed himself. Until I’ve found out for certain whether this letter implicates Robin or not, I sha’n’t give it to the police ...” “But, if Greve really had nothing to do with this shocking tragedy, the police can very easily clear him. Surely they are the best judges of his guilt ...” Again a touch of warm colour suffused the girl’s cheeks. Euan MacTavish remarked it and looked at her wistfully. “Well, well,” he observed gently, “perhaps they’re not, after all!” The girl looked up at him. “Euan, dear,” she said impulsively, “I knew you’d understand. Robin and Hartley may have had a row, but it was nothing worse. Robin is incapable of having threatened—blackmailed—Hartley, as the police seem to imagine. I am greatly upset by it all; I can’t see things clear at all; but I’m determined not to give the police a weapon like this to use against Robin until I know whether it is sharp or blunt, until I have found out what bearing, if any, this letter had on Hartley Parrish’s death ...” Euan MacTavish leant back in his chair and said nothing. He finished his cigarette, pitched the butt into the fender, and turned to Mary. He asked her to let him see the letter again. Once more he read it over. Then, handing it back to her, he said: “It’s all so simple-looking that there may well be something behind it. But, if you do go to Holland, how are you going to set about your enquiries?” “That’s where you can help me, Euan, dear,” answered the girl. “I want to find somebody at Rotterdam who will help me to make some confidential enquiries about this firm. Do you know any one? An Englishman would be best, of course ...” But Euan MacTavish was halfway to the door. “Wait there,” he commanded, “till I telephone the one man in the world who can help us.” He vanished into the hall where Mary heard him at the instrument. “We are going round to the Albany,” he said, “to see my friend, Ernest Dulkinghorn, of the War Office. He can help us if any one can. But, Mary, you must promise me one thing before we go ... you must agree to do what old Ernest tells you. You needn’t be afraid. He is the most unconventional of men, capable of even approving this madcap scheme of yours!” “I agree,” said Mary, “but how you waste time, Euan! We could have been at the Albany by this time!”