"I had this key," he said holding up a small key, "remember, word of honour! The man whom I have just left came up and wasn't certain whether he had to go in No. 8, that's the doctor's, or No. 6--_and the one key fits both doors!_" He inserted the key which was in the lock of her door and it turned easily. "And this is what I was waiting for--it was the best the poor devil could do." He lifted the paper package and broke the seals. Unfolding the paper carefully he laid it on the table, revealing a teaspoonful of what looked like fine green sawdust. "What is it?" she whispered fearfully. Somehow she knew that she was in the presence of a big elementary danger--something gross and terrible in its primitive force. "That," said Mr. Beale, choosing his words nicely, "that is a passable imitation of the Green Rust, or, as it is to me, the Green Terror." "The Green Rust? What is the Green Rust--what can it do?" she asked in bewilderment. "I hope we shall never know," he said, and in his clear eyes was a hint of terror. CHAPTER III PUNSONBY'S DISCHARGE AN EMPLOYEE Oliva Cresswell rose with the final despairing buzz of her alarm clock and conquered the almost irresistible temptation to close her eyes, just to see what it felt like. Her first impression was that she had had no sleep all night. She remembered going to bed at one and turning from side to side until three. She remembered deciding that the best thing to do was to get up, make some tea and watch the sun rise, and that whilst she was deciding whether such a step was romantic or just silly, she must have gone to sleep. Still, four hours of slumber is practically no slumber to a healthy girl and she swung her pyjama-ed legs over the side of the bed and spent quite five minutes in a fatuous admiration of her little white feet. With an effort she dragged herself to the bath-room and let the tap run. Then she put on the kettle. Half an hour later she was feeling well but unenthusiastic. When she became fully conscious, which was on her way to business, she realized she was worried. She had been made a party to a secret without her wish--and the drunken Mr. Beale, that youthful profligate, had really forced this confidence upon her. Only, and this she recalled with a start which sent her chin jerking upward (she was in the bus at the time and the conductor, thinking she was signalling him to stop, pulled the bell), only Mr. Beale was surprisingly sober and masterful for one so weak of character. Ought she to tell the doctor--Dr. van Heerden, who had been so good a friend of hers? It seemed disloyal, it was disloyal, horribly disloyal to him, to hide the fact that Mr. Beale had actually been in the doctor's room at night. But was it a coincidence that the same key opened her door and the doctor's? If it were so, it was an embarrassing coincidence. She must change the locks without delay.