Five women form the Cold Case Club to solve cold murder cases for entertainment. They have no idea what awaits them. Their successes and failures result in five murders, bringing the mystery into the lives of police and civilians as they follow the clues. Omaha Police Detective Sean O'Mally is assigned to the case the week before Christmas. During the investigation, he is surprised to learn what he left behind when he relocated to Omaha from Boston. With fresh ideas from a new source, he solves the case, takes a bullet, and changes his family as he confronts the killer.