There was an instant of silence.
Then, suddenly, traveling swiftly from right to left across the shades of the French windows, there appeared a glowing circle of brilliant white light.

Inside the circle was a black, distorted shadow--a shadow like the shadow of a gigantic black Bat! It was there--then a second later, it was gone! "Oh, my God!" wailed Lizzie from her corner.

"It's the Bat--that's his sign!" Jack Bailey made a dash for the terrace door.

But Miss Cornelia halted him peremptorily.
"Wait, Brooks!" She turned to the detective.

"Mr.Anderson, you are familiar with the sign of the Bat.