"Here you are, this 'hot shot linguist', but you can never say anything."
Little is known about Scott, other than he and Blake used to have skirmishes during their childhood, which would be remedied by a practice their mother taught them, in which they would write to each other letters about their feelings. As a result, he would have a habit of underlining words when they irritated him in some way. Later, his mother died of cancer, and after that, his brother Danny, a police officer, was killed while intervening in an armed robbery. In his adult life, Scott became a police detective for the Kansas City Police Department, which led to some irritation from him towards his father Damon, who tended to oversee the activities at the station despite retiring from his job as a police captain. The tragedies the Miller family sustained resulted in an estrangement from Blake, who went on to become a linguist and never contacted him or Damon once.
In the episode, Scott realizes that Damon called Blake over to Kansas City to investigate what appeared to be a serial killer beating and choking his victims to death with his bare hands. Scott denies that there is a serial killer active in Kansas City, but he is forced to change his mind when Damon arrives at the police station and encourages him and Blake to work together in solving the case. As a result, there is some tension between him and his sister, as evidenced when they interrogate the father of one of the first victims and Blake believes that he is lying (it turns out that he indeed was lying). Later, the BAU deduces that the unsub could be a former student or teacher at Jefferson High School, and they compile a list of people who fit their profile. Blake divides the list between herself and Scott, who further divides his half between himself and his partner.
The following night, he goes to the house of one suspect, Charles Gates, who allows him inside. Scott interviews Charles about Riley Wilson, a student who attended Jefferson High at the same time as some of the victims, and Charles tells him that the two of them were good friends. Suspicious, Scott underlines the words in his notes before being attacked by the unsub, who beats him into unconsciousness, kills Charles, and steals Scott's pistol. Damon accompanies Scott to the hospital while Blake stays behind to investigate the crime scene. By the end of the episode, the unsub is arrested, and Scott recovers from his attack. While being driven to the Miller house by Blake, Scott learns that she was shot during a previous case and points out that she never tells the family anything. Blake then reveals that she never got into contact with him or their father because she felt that she would be reminded of her mother and Danny. The two then make amends before celebrating with Damon and the entire BAU team at the Miller house.