When a 15-year-old teenager is fatally stabbed in a park in Coventry, the forensic team must identify the murderers through evidence left behind at the crime scene. But with the murder weapon nowhere to be found, the investigation relies on two key pieces of evidence: a mobile phone found a short distance from the body and the victim’s blood-soaked jacket. Through fingerprint enhancement, DNA testing and a pioneering partnership between academic researchers and the forensic team, West Midlands Police utilise a wide range of expertise in an effort to identify the killers.