DCI Gabriel Markham and his team are working to find a serial killer when a break in the case leads them to a potential culprit. Gabriel is torn between his conviction that they already know who the killer is and the seemingly irrefutable evidence found at the last murder scene. Meanwhile, there are fears that Gabriel's intimate connection to the case may be skewing his professional ability to track down the perpetrator, and his personal relationships continue to impact on his work as he is given an ultimatum to face. The rest of Gabriel's team are dealing with the conflict of their own personal and professional lives as they launch a thrilling, high-stakes operation to catch the killer. But are they targeting the right person? Gabriel makes one final connection in a desperate, last-ditch attempt to get to the truth.