Eyewitness delves into the lives of Philip and Lukas, two innocent teenage boys who bear witness to a triple-homicide while in the midst of a romantic encounter. Desperate to keep their relationship a secret they must keep what they've seen hidden from everyone, including Philip's new foster mother, Helen, a former big-city homicide detective who left her harrowing career to become a small-town sheriff. With a murderer on the loose who is desperate to silence any link to the killings, Helen will stop at nothing to solve the case and bring peace back to Tivoli.