An ordinary day for senior couple Elder and Sister Winter takes a jarring turn when they discover a dead body in the New York, New York South Mission office. Elder Winter had recently traded his LAPD Homicide Detective shield for his black and white missionary name tag. But, when the NYPD refuses to investigate, it is Sister Winter who gets the sleuth bug. Using unofficial channels and unorthodox methods, Elder and Sister Winter work together to solve the crime. Riddled with broken bones, a bomb, and a kidnapping, their mission turns out to be anything but predictable as they struggle to blend the spiritual with the temporal -- and in this case, the ultimate sin: murder.