Schoolteacher Evan Wescott stages a shooting at candidate Grant Hamilton's election campaign event and injures Hamilton and Lindsay in the process. Flack chases Wescott as he flees the scene, but he escapes when Flack stops to help a child inadvertently shot by a young boy who had picked up the gun Wescott threw into a nearby dumpster. Knowing that Lindsay had seen his face before falling unconscious, Wescott tracks her down at the hospital and attempts to kill her but isn't able to go through with it when he sees her daughter's get well card. The CSI's recover bullets from the crime scene and match the casings to a gun registered to Hamilton. They question Hamilton who claims his gun had been stolen but that he didn't want to report the theft considering the timing of his election campaign. Hawkes suspects Hamilton wasn't the target after processing the scene to discern that the shooter had been aiming at someone else near him. When the team visits Lindsay in the hospital, the steam from Danny's coffee uncovers text on the window written with a finger on prior condensation. They lift fingerprints from the "I'm sorry" message on the window and match them to Wescott. Research leads to Hamilton's VIP Beverly McCord as the likely target of the shooting as she had ruined Wescott's reputation when she accused him of inappropriate behavior after seeing him hug a child. The team tracks McCord's cell to find Wescott threatening her with a knife. Flack and Danny arrest him and place him in a lineup for Lindsay and the young boy who had used his gun, and both identify him as the fleeing shooter. Flack interrogates Wescott to learn that he stole Hamilton's gun at a fundraiser held at his beach house. Before locking him up, Flack shows Wescott the picture of the young girl who was killed using his gun to make him aware of the ramifications of his actions. Mac visits Doctor Puglisi to express his frustrations with aphasia and is upset to learn there will be no easy cure.