Peret's skepticism was written plainly on his face.
"But that is at variance with the dead man's last words. I was with M. Berjet when he died and there was certainly nothing in his actions to suggest asphyxiation. However—" He exhibited his card. "I am Jules Peret, a detective. The man that you have just pronounced dead is Max Berjet, the eminent French scientist. If he was murdered—and I have reason to believe that he was—the murderer has not yet had time to escape, as M. Berjet has been dead less than two minutes. It is possible, therefore, that I can apprehend the assassin if I act at once. Can you stay here with the body pending the arrival of the police?"
Dr. Sprague glanced at the detective's card and nodded, whereupon Peret, with a single bound, cleared the iron fence that inclosed the little yard in front of Berjet's house. As he landed, feet first, on the lawn, he heard Dr. Sprague give a piercing scream.
So startled was he by the unexpectedness of it that he lost his footing and fell forward on his face. Leaping to his feet, he whirled around and directed the beam from his flashlight on the physician.
Dr. Sprague, with his hands clawing the air in front of him, appeared to be grappling with an invisible something that was rapidly getting the best of him. His lips were drawn back in a snarl: his eyes seemed as if they were about to pop from his head, and bloody froth had begun to ooze between his clenched teeth and run from the corners of his mouth.
As Peret was preparing to leap back over the fence, he heard a terrible scream issue from the throat of the unknown pedestrian, and saw him throw up his arms as if to ward off a blow. Then the man reeled back against the fence and began to struggle desperately with something that Peret could not see.
Whipping out his automatic, the detective again vaulted the fence, but before he could reach either of them, both Dr. Sprague and the pedestrian crashed to the pavement, the first dead, the second still fighting for his life.
CHAPTER II.
THE MYSTERY DEEPENS.
ALTHOUGH the moment was obviously one that demanded caution. Jules Peret was never the man to hesitate in the face of an unknown danger.
He realized that he was in the presence of some terrible invisible thing that might strike him down at any moment, but, as he had no idea what that thing was and could not hope to cope with it until it attacked him or in some manner made itself manifest, he dismissed it from his mind for the moment and turned his attention to the two men who had gone down before its onslaught.
Kneeling beside Dr. Sprague's prostrate form, he bent over and peered in the physician's face. One look at the horribly distorted features and the glassy eves that stared into his own, told him that the man was dead.
Turning now from the dead to the living, Peret jumped to his feet and ran to help the pedestrian who, with the help of the terrified little druggist, was in the act of staggering to his feet. Although the druggist's teeth were chattering with fear, his first thought seemed to be for the sufferer, and he helped Peret support the man, too weak to stand unaided, when he reeled back against the fence.
Choking, gasping, spitting, the pedestrian fought manfully to regain his breath. His face was purple with congested blood, and his glazed eyes were bulging. Great beads of sweat poured from his forehead and mingling with the froth that oozed from between his lips, flecked his face as he
