He stood critically observing the scene, with all outward appearance of calmness.

Agnes had not seen him. She was making desperate efforts to raise Sprague's limp form; but felt herself succumbing to the effects of the gas.

"My darling! my poor darling!" she exclaimed, and suddenly she staggered and lurched forward.

Sturgis made an instinctive effort to support her; but before he could reach her Murdock was at her side and had her in his arms. He bore her gently up the stairs and into his study. Then, for an instant, he seemed to hesitate. The reporter expected to see him close the door. Instinctively his hand reached back to his hip pocket for his revolver. But, in another moment, Murdock had returned to where he stood.

"Come!" he said.

At the same time he lifted the artist in his arms and carried him up the stairs. Sturgis followed unsteadily and reached the study, only to fall exhausted into a chair.

Having deposited his burden upon the floor, Murdock closed the door of the death chamber; turned a valve which was near his desk; opened the windows wide, and revolved a crank which projected from the wall near the door of the extension.

"He is shutting off the gas and opening the steel shutters of the skylight," thought Sturgis.

Then the chemist produced a flask and poured out a small quantity of brandy, which he forced his daughter to swallow.

As soon as she was sufficiently revived, she rushed to the side of her lover, whose head she gently raised to her lap. Murdock's eyes were fastened upon her. She met his calm questioning gaze.