Jo's car is run off the road by a lorry. The driver may be guilty of dangerous driving. Dr Hardy receives a letter threatening his wife's life and demanding he change his evidence. Hardy refuses but it is at the risk of his wife's life.

Dr. Hardy is involved in tracing a ruthless psychotic killer who is employed by the accused in an attempt to suborn witnesses. He is determined to give his evidence, but the police issue firearms to protect his life.