New case of Isaac Bell - an employee of the best detective agency in New York! 1908, USA. A famous engineer who was working on a new type of cannon for warships dies under mysterious circumstances. His daughter, convinced that her father was killed, contacts Van Dorn's agency. Isaac Bell, who is entrusted with the investigation, understands: the death of the gunsmith is not an accident. Indeed, several military engineers have already died under mysterious circumstances recently. There is clearly an experienced, intelligent and ruthless killer operating in the country... But who is he working for? How to figure it out and grab it?..