A 32-year-old man and his 57-year-old father have been murdered, each man shot dead with a shotgun at point blank range at their homes in villages 10 miles apart in a quiet part of Cambridgeshire. After a county-wide manhunt, police have three suspects in custody. At the centre of the tragic crime is a dispute over the custody of a child. Detectives believe that they have compelling evidence that the child's grandfather was directly responsible. But did he act alone? Can text messages and CCTV prove a wider conspiracy to murder? Cameras follow as the double murder investigation reaches its final dramatic conclusion.