On the eve of Valentine's Day, 2021, a private birthday celebration in a sleepy coastal town ended in bloody murder. During the trial later that year, recordings of the call and video footage taken from police bodycams of the subsequent arrest were beamed around the world. Sixty-six-year-old Penny Jackson, a retired accountant, had murdered her ex-army officer husband, David Jackson, with a paring knife; coldly stabbing him on three separate occasions before calmly phoning the emergency services as he lay bleeding to death on their kitchen floor. In this series - with revealing interviews from David Jackson's sister, Jenny, and his estranged brother Alan - we reveal the dark and disturbing secrets which lay behind this seemingly inexplicable and brutal slaying.