The Assistant

The Assistant is a standalone, historical crime thriller, which is set across two timelines. The first is 1924/25 during prohibition, and the second is 1938, with the backdrop of the Nazi invasion.
The main characters are Jack Rivers who, during the prohibition era, helped to smuggle spirits from Oslo (then known as Kristiania) to the surrounding areas, and Ludvig Paase, who was a police officer during prohibition, but later became a private investigator. In 1938, Jack Rivers became Paase's assistant.
The two timelines may seem confusing at first, but the further you read, the more you realise how the events in one timeline have caused the events in the other.
There is a dark undertone to the narrative, but The Assistant is a gripping read that moves along at a steady pace.