Boyd receives an anonymous package in the post – a Nazi ceremonial dagger. Attached to it is a Cold Case number, linking it to the unsolved murder of a young girl in May 1945. It seems that Mel had been working on the case before her death, what does this mean for the Cold Case Team?

As Ben goes missing, Boyd and his team try to force the truth out of a confused David. Boyd grows increasingly close to Sarah, and Stella travels to Poland to investigate the true story.