Astraia Holmes, sister of Sherlock, is baffled by a series of bizarre and brutal murders committed by a dragon-like assailant, and desperately wishing to impress her brother and solve the crimes she teams up with a mysterious and brilliant young woman, Madeleine Barquist. Sherlock suspects an ancient malevolence at work and he fears for Astraia's safety. The signs point to a Chinese Dragon God Cult known as the Ya Zi, a warrior society originally formed two thousand years ago to assassinate enemies of the Emperor. Astraia is exultant to finally have a chance to use her own deduction skills, but Miss Barquist is fearful to meet the eye of Sherlock Holmes-for unknown to both Astraia and Sherlock, she is the daughter of Jack the Ripper, and unknown to them all, a dark and powerful evil is preparing to strike at the heart of London.

Daintily, almost like a spirit, she glided beyond the frightening calligraphy to stand before the brick wall of Mr. Wu's building. Raising her lantern to the structure, she pointed her magnifying glass toward a section near the door. "What do you see here?" she asked, holding her glass implement to the wall as aid to my inspection.

I followed her, not half so ethereal. I have always been a clodhopper of a girl. I stared through the lens at the wall.

"The brick has been gouged," I said, removing a glove to lightly run a finger along a furrow incised into the masonry.

"You see there are three grooves, in fact, each almost a foot in length, separated by approximately three inches at the left end of the gouge and closer to five inches distance from each other at the right end," she said. "Do you have any theories about what could have created them?"

"I have no idea," I said, moving my finger over the lowest furrow, carved perhaps a half-inch deep into the brick. "But I don't believe I saw them when I was here last week."

"No, I don't expect you did," she said. "These gouges are fresh. You can see the brick dust from them on the ground, still unspoilt by the alleyway filth."

I lowered my own lantern to examine the ground, and saw that she was right. "What type of instrument was used to make such delineations?" I asked. "A knife or sword?"