A flash mob is a harmless pastime for people looking for entertainment. The game surprises, amuses, puzzles—and sometimes scares the audience. But it doesn’t cause harm… at least not until a certain moment… Until one smart and calculating person figures out how to use this entertainment for their own purposes. And then, at the “mobs,” people begin to die. Solving these murders is extremely difficult because there are no witnesses, no traces—there are simply too many people. But if you can find who benefits from it, everything will fall into place—and the criminal can be unmasked. That’s exactly what the main characters of this book do.