He stepped forward along an unlighted hall, opened a door, and slammed it behind him. He switched on the light. He was in his consulting room. The next instant he was standing beside his desk, and had wrenched John Bruce's letter from his pocket. He spread this out on the desk and glared at it. Beyond any doubt whatever, where Claire's tears had fallen on the paper, traces of writing were faintly discernible. Here, out of an abortive word, was a well-formed “e”; and there, unmistakably, was a capital “L.” Crang burst into a torrent of abuse and oaths; his fists clenched, and he shook one of them in the air. “Double-crossed--eh?--damn him!” he choked. “He tried to double-cross me--did he?” Carrying the letter, he ran now into a little room behind his office, where he compounded his medicines, and that was fitted up as a sort of small laboratory. “I'm a clever man,” Crang mumbled to himself. “We'll see about this!” With sudden complacence he began to study the sheet of paper. He nodded curtly to himself as he noted that the traces of the secret writing were all on the lower edge of the paper. “We'll be very careful, _very_ careful”--Doctor Crang was still mumbling--“it may be useful in more ways than one.” He turned on the water faucet, wet a camel's-hair brush, and applied the brush to the lower edge of the letter. The experiment was productive of no result. He stared at the paper for a while with wrinkled brow, and then suddenly he began to laugh ironically. “No, of course, not!” He was jeering at himself now. “Clever? You are not clever, you are a fool! She _cried_ on the paper. Tears! Tears possess a slight trace of”--he reached quickly for a glass container, and began to prepare a solution of some sort--“a very slight trace... that's why the characters that already show are so faint. Now we'll see, Mr. John Bruce, what you've got to say.... Salt!... A little salt, eh?” He dipped the camel's-hair brush in the solution and drew it across the bottom edge of the paper again. “Ha, ha!” exclaimed Doctor Crang in eager excitement. Letters, words and sentences began to take form under the brush. “Ha, ha! He'd play that game with me, would he? Damn him!” Very carefully Sydney Angus Crang, M.D., worked his brush upward on the paper line by line, until, still well below the signature that John Bruce had affixed in his, Crang's, presence, there failed to appear any further trace of the secret writing. He read as fast as a word appeared--like a starving beast snatching in ferocious greed at morsels of food. It made whole and complete sense. His eyes feasted on it now in its entirety: Keep away. This is a trap. Stall till you can turn tables. Information obtained while I was delirious. Am a prisoner in hands of a gang whose leader is a doctor named Crang. Veniza will tell you where Crang lives. Get Veniza's address from Lavergne at the house. The only way to save either of Us is to trick Crang. Look out for yourself. Bruce.