On a quiet Sunday lunchtime in a Cambridgeshire suburb, a man lies bleeding to death. A major manhunt is triggered, where the strength of family blood ties is brutally exposed.

The first episode of a two-part special taking viewers behind the scenes of a Major Crime Unit investigation into the death of an 11-week-old baby after 11 days in intensive care. During this time, the police are watching the parents intently for fear they may have harmed the child - concerns that seem to be borne out when the scale of the child's injuries is revealed by an autopsy.