“Look!” cried Janet Cranston, in a frightened voice, from the back of the car.

The light of the phonometer had flashed up.  A car was following us.

“There’s just one chance!” cried Kennedy, springing to the wheel.  “We might make it on the rim.”

Banging and pounding, we forged ahead, straining our eyes to watch the road, the distance, the time, and the phonometer all at once.

It was no use.  A big gray roadster was overtaking us.  The driver crowded us over to the very edge of the road, then shot ahead, and, where the road narrowed down, deliberately pulled up across the road in such a way that we had to run into him or stop.

Quickly Craig’s automatic gleamed in the dim beams from the side lights.

“Just a minute,” cautioned a voice.  “It was a plot against me, quite as much as it was against her—­the nurse to lead me on, while the doctor got a rich patient.  I suspected all was not right.  That’s why I gave you the card.  I knew you didn’t come from Burr.  Then, when I heard nothing from you, I let the Giles woman think I was coming to Montrose to be with her.  But, really, I wanted to beat that fake asylum—­”

Two piercing headlights shone down the road back of us.  We waited a moment until they, too, came to a stop.

“Here they are!” shouted the voice of a man, as he jumped out, followed by a woman.

Kennedy stepped forward, waving his automatic menacingly.

“You are under arrest for conspiracy—­both of you!” he cried, as we recognized Doctor Burr and Miss Giles.

A little cry behind me startled me, and I turned.  Janet Cranston had flung herself into the arms of the only person who could heal her wounded soul.

IV

THE MYSTIC POISONER

“It’s almost as though he had been struck down by a spirit hand, Kennedy.”

Grady, the house detective of the Prince Edward Charles Hotel, had routed us out of bed in the middle of the night with a hurried call for help, and now met us in the lobby of the fashionable hostelry.  All that he had said over the wire was that there had been a murder—­“an Englishman, a Captain Shirley.”

“Why,” exclaimed Grady, lowering his voice as he led us through the lobby, “it’s the most mysterious thing, I think, that I’ve ever seen!”

“In what way?” prompted Kennedy.

“Well,” continued Grady, “it must have been just a bit after midnight that one of the elevator-boys heard what sounded like a muffled report in a room on the tenth floor.  There were other employees and some guests about at the time, and it was only a matter of seconds before they were on the spot.  Finally, the sound was located as having come probably from Captain Shirley’s room.  But the door was locked—­on the inside.  There was no response, although some one had seen him ride up in the elevator scarcely five minutes