A lot of nerves were shot to blazes, a couple fainted, but our eagle eyes failed to discover a guilty face. However," he went on, dropping this sardonic humor, "we did learn one thing, which was the main purpose, and that was the time element. The consensus of opinion, as we clocked the time, was that the lights were not out more than three minutes, though one or two estimated as much as five.

"So, to all appearances, the lights could not have been switched off and on, with the murder sandwiched in between, by one and the same person. I say to all appearances, but this is a mystery within a mystery. Were we to solve the modus operandi of the murder, we would still be confronted with the problem of the slayer.

"All that I have really got is one thing from the dead woman's maid. About a week ago, Helene Storme received a phone call that left her faint and sick. Her words, according to the maid were: 'No money can repay me for my sufferings. I will make you pay in my own way.'"

"By Jove!" exclaimed Dawson. "That looks like she was out to get somebody—and somebody got her!"

COROT nodded slowly and studied the ash on his cigar. "I'll tell you, Dawson," he said presently, "I am not at all satisfied with myself in this case. I feel I am overlooking something that may be right under my nose. I—" He stopped suddenly, his eyes burning. "By the Lord!" he shot out sharply. "I've got it! I believe this is a trick murder! And I'm going to find out!"

He was out of his chair, rushing into the street and leaping into his car as Dawson catapulted himself into the rear seat. But not another word was spoken by Corot on the way to the Ajax Studios, and Dawson was reporter enough to know when to remain silent.

Inside the gate they encountered Detective Carroll.

"Inspector," he said in a husky whisper, "we're checking up on everybody who was in the studio, but we couldn't find a trace of that knife, though three of us searched all night."