The rain began on March 16, 1936, and with it, the rain came pain. Raymond Twigg hates the rain because it gives the Rain Man power. It is a power to bring Raymond to his knees or drive him to deadly action.
As the March 1936 rains bring the St. Patrick's Day Flood, the worst flood ever seen in Cumberland, Maryland, it also unleashes the power of the Rain Man on the citizens of the city.
While most of the police force is diverted trying to deal with the flooding in the city and the problems it is causing, Sergeant Jake Fairgrieve is called out to investigate a murder. Murders are unusual in Cumberland, but this one is more unusual than most. The dead man's head has been crushed on the left side with no apparent weapon and the body is laid out on the street as if it was in a casket.
Jake throws himself into tracking this murder with no motive. The search keeps him from having to deal with his own fears about the approaching flood until he comes face to face with the Rain Man.
With the Jake trailing him, the Rain Man turns from hunted to hunter. He kidnaps Jake's girlfriend, Dr. Chris Evans. In order to save Chris, Jake will have to face his own fears and the Rain Man in the flooded streets of Cumberland where the Rain Man is at his most powerful.