The silver city is Aberdeen, capital of the North Sea oil industry, and it is here that Keith Calder is summoned to give evidence in the trial of Hugh Donald for murder...Keith's ballistic evidence proves unexpected and the result is that peculiarly Scottish verdict - Not Proven.But 'Not Proven' is a long way from 'Not Guilty'. Hugh Donald is employed by one of the giants in the oil industry. His position, in which he holds the financial power to make or break contractors, is one which demands trust. Hugh Donald and his employers are jointly determined that his name must be cleared.Donald and his solicitor, Jeremy Prather, persuade Keith to reinvestigate in the hope of finding the real killer. The evidence is months old, but they have two starting the substitution of another gun in place of the murder weapon and the conviction that the motive is connected to Donald's working life.Will they be able to unravel the crime?As we have come to expect from Gerald Hammond, this is a whodunnit of ingenuity and tension with Keith Calder's own particular brand of humour.Born in 1926, Gerald Hammond lived in Scotland, where he retired from his profession as an architect in 1982 to pursue his love of shooting and fishing and to write full time. After his first novel, Fred in Situ , was published in 1965, Gerald became a prolific author with over 70 published novels. Most of his novels were published under his own name, but he also wrote under the pseudonyms Arthur Douglas and Dalby Holden.