 Catherine Willows processed evidence which helped placed John Mathers on death sentence for the rape and murder of a university student 15 years ago. Seconds, literally, before Mathers was to received his sentence, a call reaches the execution room to postpone the execution. Mathers, who has already received the lethal drug, is revived back. The defending attorney has asked for the 15-year-old evidence to be reprocessed using new technologies not available back then. Matters become more complicated when another murder, exactly like that of the university student, occurs on the university campus, prompting the detectives to believe that there is still a killer out on the loose.