Five years ago, on a bridge in Shanghai, Dr. Keppel Harkness saw a figure that should not have existed: a cowled shape with no face, moving through the crowd as though the world itself made way for it. A child warned him that the Scorpion was coming. A colleague pressed a sealed envelope into his hands and told him to keep it safe.

Then life went on.

Until the sound begins.

In his quiet London home, Harkness hears a low vibration that leaves no trace on any recording. His security cameras fail. A cloaked figure appears in his garden. And at his medical practice, a mysterious woman calling herself Mademoiselle Dorian arrives with agonising headaches and a metallic implant buried at the base of her skull.

When Harkness asks what it is, she gives him a single answer:

A leash.

Soon Scotland Yard is at his door with a body from the Thames and a gold-plated scorpion stinger designed to deliver a poison no laboratory can detect. The victim may be a legendary French intelligence operative. The killer may belong to an organisation older, richer, and more patient than any government hunting it. Its name is whispered across intelligence files and dying messages: the Scorpion.

As Harkness is drawn into a conspiracy of synthetic toxins, surveillance, blackmail, and impossible technology, he discovers that the Scorpion does not merely kill. It owns. It infiltrates. It waits. And its master, the veiled Han-Zo, has marked Harkness for a purpose he does not yet understand.

To survive, Harkness must trust a woman trained to deceive him, a detective with secrets of his own, and a dead man who may not be dead after all. But every answer brings him closer to the heart of a shadow empire — and to a weapon that could change the balance of power across the world.

The Scorpion has waited centuries.

Now it is ready to strike.