aimed Miss Laidlaw.

Plainly there was a muffled scream of a woman as we entered the street
door. I hurried forward. It was the work of only a few seconds to batter
down the locked door in the room under Creighton's old workshop, and as
the door gave way, I heard the sound of shattered glass from the rear
which told that Kennedy had heard the scream, too, and had gained an
entrance.

Inside I could make out in the half-light a man and a woman. The woman
was running toward me, as if for help.

"Mrs. Barry!" gasped Adele Laidlaw.

"He got me here--to kill me!" she cried hysterically. "I am the only one
who knows the truth--it was the last day--tonight he would have had the
money--and I would have been out of the way. But I'll expose him--I'll
ruin him. See--he came in from the roof--"

A blinding flash of light greeted us, followed by a scream from Adele
Laidlaw, as she ran past us and dropped on her knees beside a body that
had fallen with a thud in the flame before a yawning hole in the side
wall.

Mrs. Barry ran past me, back again, at almost the same moment. It was a
strange sight--these two women glaring at each other over the prostrate
figure of the man.

"Here's the real demon engine," panted Craig, coming up from the back
and pointing to an electric motor as well as other apparatus consisting
of several series of coils. "The perpetual motion machine was just a
fake. It was merely a cover to an attempt to break into the bank vaults
by electrolysis of the steel and concrete. Creighton was a dummy, a
fiction--to take the blame and disappear when the robbery was
discovered."

"Creighton," I repeated, looking at the man on the floor, "a dummy?"

"Oh--he's dead!" wailed Adele Laidlaw. "He's dead!"

"Electrocuted by his own machine rather than face disgrace and
disbarment," cut in Craig. "No wonder she was in doubt which of the two
men fascinated her most."

I moved forward and bent over the contorted form of the lawyer, Tresham,
who was wearing the whiskers and iron gray wig of his alter-ego,
Creighton.

CHAPTER XXVIII

THE CANCER HOUSE

"You've heard of such things as cancer houses, I suppose, Professor
Kennedy?"

It was early in the morning and Craig's client, Myra Moreton, as she
introduced herself, had been waiting at the laboratory door in a state
of great agitation as we came up. Just because her beautiful face was
pale and haggard with worry, she was a pathetic figure, as she stood
t