The Twenty-Three: Linwood Barclay

The day begins like any other Saturday - a shower, coffee, breakfast. But suddenly, all hell breaks loose in the town of Promise Falls. People are dying in the street - the hospital and emergency services are overwhelmed by sheer numbers. Is it mass food poisoning, a virus, or something more sinister? Has someone, rather than something, caused this?
Detective Barry Duckworth is already investigating two murders and an explosion at the town's drive-in. He starts to wonder if these crimes and the new attacks are connected to the mysterious incidents in Promise Falls involving the number twenty-three.
But who is sending these deadly messages, and how can they be stopped?