I was desperate.

I threatened him with the revolver but he took it from me.
Then when I tore the blue-print from him--he was shot--from the stairs--" "By Bailey!" interjected Beresford angrily.
"I didn't even know he was in the house!" Bailey's answer was as instant as it was hot.

Meanwhile, the Doctor had entered the room, hardly noticed, in the middle of Dale's confession, and now stood watching the scene intently from a post by the door.
"What did you do with the blue-print ?" The detective's voice beat at Dale like a whip.
"I put it first in the neck of my dress--" she faltered.

"Then, when I found you were watching me, I hid it somewhere else." Her eyes fell on the Doctor.

She saw his hand steal out toward the knob of the door.