SPOILERS:-

A serial killer attacks a local club, injurying and murdering several patrons. Clark arrives and discovers Davis's body, covered in blood and lying unconscious on the floor. Davis denies any memory of the event. While looking for clues, Clark meets John Jones, who, since losing his powers, has taken a job as a police detective. John and Clark work together on the attack, with John indicating that there have been others and that Davis has been the first to arrive on each of the scenes. Davis discovers that the blood on his body is not his, and that he has no wounds; Davis starts to believe that he is the killer because he suffers blackouts during the attacks, and finds his skin under the fingernail of a victim. One of Chloe's Isis clients attacks Davis and Jimmy, and after Clark subdues him, the client confesses to all of the murders. John warns Clark that his heroic attacks are getting a lot of attention and could expose him to the world, so he needs to be more careful when saving people.