"Last night at the Aberdeen Proving Ground in Maryland. It has killed eight or ten and twice as many more are sick. The place is quarantined and a rigid censorship has been placed over the telephones, but it is only a matter of time before some press man will get the story. I have a car waiting below and a pass signed by the Secretary of War. Grab what apparatus you need and we'll start." Dr. Bird pressed a button on his desk. A tall, willowy girl entered, notebook in hand. Carnes glanced with keen appreciation at her slim beauty. "Miss Andrews," said the doctor, "in five minutes Mr. Carnes and I will leave here for Aberdeen Proving Ground in the Government car which is waiting below. You will see that Mr. Davis is in that car and that traveling laboratory 'Q' is ready to follow us." "Yes, Doctor." "You remember that mysterious plague in Belgium last December, do you not?" "Yes, Doctor." "I was unable to get over to Belgium, but an army surgeon and two Public Health Service men went over. You will get copies of all reports they made, including especially any reports of autopsies on bodies of victims. I want all data on file in the Public Health Service or the War Department. You will then obtain a car and follow us to Aberdeen. Arrangements will be made for your admittance to the proving ground. The Belgian plague has made its appearance in the United States." * * * * * Swiftly the expression of the girl's face changed. Her dark eyes glowed with an internal fire and the immobility of her face vanished as if by magic to be replaced by an expression of fierce hatred. Her lips drew back, exposing her strong white teeth and she literally spat out her words. "That swine, Saranoff!" she hissed. Carnes sprang to his feet. "Why, it's Feodrovna Androvitch!" he cried in astonishment. In an instant the rage faded from her face and the calm, immobility which had marked it reappeared. Through the silence Dr. Bird's voice cut like a whip. "Miss Andrews," he said sternly, "I thought that I had impressed on you the fact that even a momentary lapse from the character which you have assumed may easily be fatal to both of us. Unless you can learn to control your emotions, your usefulness to me is at an end." Although Carnes watched closely he could not detect the slightest change of expression in the girl's face as the doctor spoke. "I am very sorry, Doctor," she said evenly. "We were alone and I allowed the mask to slip for an instant. It will not happen again." "It _must_ not," said the doctor curtly. "Carry out your instructions." "Yes, Doctor." She turned on her heel and left the office. Carnes looked quickly at Dr. Bird. "Surely that is Feodrovna Androvitch, Doctor?" he asked. "It was. It is now Thelma Andrews, my secretary. She changed her name with her appearance and politics. I have been training her since last August. This is her first official appearance, so to speak."