Forensic science is one of the most powerful tools in any criminal investigation. The impartial and objective evidence it provides can help exonerate the innocent and convict the guilty. Professor Angela Gallop has been at the forefront of forensics for more than 45 years. During her remarkable career, she has worked on thousands of cases in the UK and around the world. Now, for the first time, she goes into detail describing some of those cases, explaining the wide range of skills and techniques that she and her colleagues have used to solve them. From looking at blood patterns and footwear marks, to analysing fragments of glass, paint and textile fibres, Gallop shows that every contact really does leave a trace and every trace can help solve a crime.