A murder-free spell in Minneapolis is shattered when two elderly men are found murdered in one night – both self-sufficient, utterly innocent, and beloved. As the victim toll mounts, homicide detectives Leo Magozzi and Gino Rolseth struggle to find a connection between victims in a demographic group rarely targeted by serial killers, and find elusive threads that uncover a series of horrendous secrets, some buried within the heart of the police department itself, blurring the lines between heroes and villains. Grace MacBride's cold-case-solving software may find the missing link – but at a terrible price.