The CSI's find Vernon Academy student Luke Stevenson murdered in the library where he was studying for the SATs the night before. Dr. Hawkes finds dextroamphetamines (ADHD medication) in Luke's backpack. Mac breaks the news to Luke's father, A.D.A. Frank Stevenson, who tells him that his son didn't have ADHD and notes that Luke's friend Nate recently OD'd on prescription meds. Nate' autopsy report shows dextroamphetamines in his system leading the CSI's to believe Luke was selling the drug. They run prints on the bag containing the pills and Billy Wharton, a student Luke was fighting with the day before, is pulled up as a match. Billy claims the pills were his prescribed ADHD medication, but Luke's father Frank uses his connections to subpoena Billy's psychiatric records which show that he had gone to various psychiatrists to get prescriptions for the drug from all of them. Danny finds a ripped page in the middle of Luke's notebook and recovers the text from the pen indentations on the following page to learn that Luke was going to blow the whistle on students using dextroamphetamines to gain a competitive edge. After Adam cracks the code of Billy's cell phone texts to determine he was using Algebra problems to secretly arrange drug deals, they interrogate him and he gives up Mr. Connors, the teacher who broke up the fight between Billy and Luke the day before. When they interrogate Mr. Connors, he confesses to being aware of the drug dealing and not stopping it since he wanted the acclaim of having the smartest students. Mr. Connors had confronted Luke about his planned expose and killed him when he refused to back down. Lindsay attends the execution of a man who sexually assaulted her friends when she was a teenager and gets closure on the incident.