The amount of money to be made in the movies had resulted, in the case of Manton, in luxurious equipment for all the various departments of his establishment.  I had noticed the offices, furnished with a richness worthy of a bank or some great downtown institution.  Now, in the lavatory, immaculate with its white tile and modern appointments, I saw a shelf literally stacked, in this day of paper, with linen towels of the finest quality.

As I drew the water, hot instantly, my eye caught, half in and half out of the wire basket beneath the stand, one of the towels covered with peculiar yellow spots.  Immediately my suspicions were awakened.  I picked it up gingerly.  At close range I saw that the spots were only chrome yellow make-up, but there were also spots of a different nature.  I did not stop to think of the unlikeliness of the discovery of a real clue under these circumstances, analyzed afterward by Kennedy.  I folded the towel hastily and hurried to rejoin him, to show it to him.

I found him with Werner, waiting for the results of Manton’s efforts to locate Millard.  Almost at the moment I rejoined the two a boy came to summon Werner to one of the sets out on the stage itself.  Kennedy and I were alone.  I showed him the towel.

At first he laughed, “You’ll never make a detective, Walter,” he remarked.  “This is only simple coloring matter-Chinese yellow, to be exact.  And will you tell me, too”—­he became ironical—­“how do you expect to find clues of this sort here for a murder committed in Tarrytown when all the people present were held out there and examined, when we are the first to arrive back here?

“Yellow, you know, photographs white.  Chinese yellow is used largely in studios in place of white in make-up because it does not cause halation, which, to the picture people, is the bane of their existence.  White is too glaring, reflects rays that blur the photography sometimes.

“If you will notice, the next time you see them shooting a scene, you will find the actors’ faces tinged with yellow.  Even tablecloths and napkins and ‘white’ dresses are frequently colored a pale yellow, although pale blue has the actinic qualities of white for this purpose, and is now perhaps more frequently used than yellow.”

I was properly chastened.  In fact, though I did not say much, I almost determined to let him conduct his case himself.

Kennedy saw my crestfallen expression and understood.  He was about to say something encouraging, as he handed back the towel, when his eye fell on the other end of it, which, indeed, I myself had noticed.

He sobered instantly and studied the other spots.  Indeed, I had not examined them closely myself.  They were the very faint stains of some other yellow substance, a liquid which had dried and did not rub off as the make-up, and there were also some small round drops of dark red, almost hidden in the fancy red scrollwork of the lettering on the towel, “Manton Pictures, Inc.”  The latter had escaped me altogether.