August 2010. The Tobins - a happy, well-off family - spend a sunny afternoon at a birthday party with friends. By dawn, most of them are dead. It's a crime that grabs headlines and shocks the nation. The key suspect, Aidan Tobin, was known as a loving husband and father, but his desperate attempt to take his own life is as good as a confession. The case begins and ends with him. August 2021. A survivor of the attacks regains a memory of that horrific night. Chloë Tobin never believed her father was guilty. Only six at the time, she is the sole witness to the brutal attacks. Now, she insists that somebody else was involved. Could she be right? DI Matt Lockyer and DC Gemma Broad of Wiltshire Police's cold case unit aren't so sure. But as they begin to investigate, they soon discover there's more to this case than meets the eye. After all, why would a man who had everything destroy it all?