Chan Ho-Kei’s The Borrowed was one of the most acclaimed international crime novels of recent years, a vivid and compelling tale of power, corruption, and the law, spanning five decades of the history of Hong Kong. Now he delivers Second Sister, an up-to-the-minute tale of a Darwinian digital city where everyone from tech entrepreneurs to teenagers is struggling for the top.

A schoolgirl—Siu-Man—has committed suicide, leaping from her twenty-second floor window to the pavement below. Siu-Man was an orphan, and Nga-Yee, the librarian older sister who’d been raising her, refuses to believe there was no foul play—although nothing seemed amiss. She contacts a man known only as N—a hacker and an expert in cyber-security and manipulating human behavior. But can Nga-Yee interest him sufficiently to take her case, and can she afford it if he says yes?

What follows is a cat-and-mouse game through the city of Hong Kong and its digital underground, especially an online gossip platform, where someone has been slandering Siu-Man.

The novel is also populated by a man harassing girls on mass transit; high school kids, with their competing agendas and social dramas; a Hong Kong digital company courting an American venture capitalist; and the Triads, market women and noodle shop proprietors who frequent N’s neighborhood of Sai Wan.

In the end, it all comes together to tell us who caused Siu-Man’s death and why, and to ask—in a world where online and offline dialogue has forgotten about the real people on the other end—what is the proper punishment?