There are few criminal cases more astonishing yet less well known than that of Graham Young.

A quintessentially British crime story set in the post-war London suburbs, it involves two sensational trials, murders both certain and probable, a clutch of forgiving relatives, and scores of surviving victims. Fourteen in the summer of 1962, Graham stood in the Old Bailey dock charged with poisoning a schoolfriend and family members by adding antimony to their packed lunches, Sunday roast and morning cups of tea.

Diagnosed with multiple personality disorders, Graham's trial resulted in his detainment at Broadmoor, where he was the youngest patient. But it was on his release from Broadmoor that Graham caused the greatest harm.

Finding employment in Hadlands, a photographic supplies firm, his role as junior storeman meant he was expected to make tea and coffee for his colleagues. And very soon, numerous members of staff began experiencing crippling stomach pains...