This documentary takes two cases, the killing of a woman in Rhineland Palatinate, Germany, and the murder of a hospital nurse in Glasgow, to demonstrate how the entomologist Jens Amendt and the forensic soil expert Lorna Dawson work.

In the laboratory, molecular biologist Dr. Harald Schneider extracts DNA from very small traces, and 0.5 square millimeters are enough to identify genetic material.

Investigators wonder whether a victim was shot with a weapon found at the scene of the crime, and molecular ballistics can help clarify.