"Dark Minds" brings together the sharp criminal minds of author and investigative journalist M. William Phelps and pre-eminent criminal profiler John Kelly to reopen unsolved homicides thought to be the work of serial killers. They are assisted in their efforts by a source known only to viewers as "13," a convict serving multiple life terms for a series of murders, who presents Phelps and Kelly with theories on the homicides based on his own experiences. In addition to the information helping the hosts build portraits of the suspects, the hope is that the renewed investigations will jog the public's memories and encourage viewers to bring forward new leads.