Angel read:-- “The word of five letters I will use, namely: 1. White every 24 sec. 2. Fixed white and red. 3. White group two every 30 sec. 4. Group occ. white red sec. 30 sec. 5. Fixed white and red.” Underneath was written: “No good; too easy.” The detective’s brows were bent in perplexity. “I’m blessed if I can see where the easiness comes in,” he said. “To me it seems so much gibberish, and as difficult as the other.” Jimmy noted the detective’s bewilderment with a quiet smile of satisfaction. He did not look directly at the girl, but out of the corner of his eyes he could see her eager young face bent over the card, her pretty forehead wrinkled in a despairing attempt to decipher the curious document. “Yet it was easy,” he said, “and if Reale had stuck to that word, the safe would have been opened by now.” Angel pored over the mysterious clue. “The word, as far as I can gather,” said Jimmy, “is ‘smock,’ but it may be----” “How on earth----” began Angel in amazement. “Oh, it’s easy,” said Jimmy cheerfully, “and I am surprised that an old traveler like yourself should have missed it.” “Group occ. white red sec. 30 sec.,” read Angel. Jimmy laughed. It was the first time the girl had seen this strange man throw aside his habitual restraint, and she noted with an unaccountable satisfaction that he was decidedly handsome when amused. “Let me translate it for you,” said Jimmy. “Let me expand it into, ‘Group occulting White with Red Sectors every Thirty Seconds.’ Now do you understand?” Angel shook his head. “You may think I am shockingly dense,” he said frankly, “but even with your lucid explanation I am still in the dark.” Jimmy chuckled. “Suppose you went to Dover to-night, and sat at the end of the Admiralty Pier. It is a beautiful night, with stars in the sky, and you are looking toward France, and you see----?” “Nothing,” said Angel slowly; “a few ships’ lights, perhaps, and the flash of the Calais Lighthouse----” “The occulting flash?” suggested Jimmy. “The occ.! By Jove!” “Glad you see it,” said Jimmy briskly. “What old Reale did was to take the names of five famous lights--any nautical almanac will give you them: Sanda. Milford Haven. Orkneys. Caldy Island. Kinnaird Head. They form an acrostic, and the initial letters form the work ‘smock’; but it was too easy--and too hard, because there are two or three lights, particularly the fixed lights, that are exactly the same, so he dropped _that_ idea.” Angel breathed an admiring sigh. “Jimmy, you’re a wonder,” he said simply. Jimmy, busying himself amongst the papers, stole a glance at the girl. “I am very human,” he thought, and was annoyed at the discovery. “Now we come to the more important clue,” he said, and smoothed a crumpled paper on the table. “This, I believe, to have a direct bearing on the verse.” Then three heads came close together over the scrawled sheet.