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 his theories about potential motivations behind these chilling cold cases based on his own experiences. They bring fresh eyes to unsolved serial killer investigations using the combined instincts of three unique perspectives, with hopes that it will encourage viewers to bring forward new leads.