In his Four Just Men series, Edgar Wallace comes up with something different: the villains are not necessarily bad people, and the pursuers of justice, the Four Just Men, as they call themselves, are acting outside the law. They argue that their actions are for the public good, and dispassionately eke the ultimate revenge death on their victims.
The first message sent to Tom Thorne's phone was just a picture - the blurred image of a man's face, but Thorne had seen enough dead bodies to know that the man was no longer alive. But who was he? Who sent the photograph? And why? While the technical experts attempt to trace the sender, Thorne searches the bulletins for a reported death that matches the photograph. Then another picture arrives.