A woman, Rhonda Kirkman, unwraps a package and inside is a book, which explodes, but she and her daughter Sophia survive. J.J. returns to work after recovering from being shot. The BAU has been called in to investigate a series of bombings in Ohio, Tennessee, and Kentucky. The unsub is unusual because he's hand-delivering the bombs and hasn't revealed any ideology. Working from home, Simmons declares the bomb assembly identical in all three blasts, with the bombs detonated remotely. The unsub takes photos of the package being picked up and of its explosion and sends funeral notices to the victims' families. He sets off another bomb in Tennessee. Reid has the Kirkmans look at photos of the other victims' family members. Three of them had been on a cruise with the parents and the quintet had rented a car together to tour the countryside. The unsub, carrying a gift, talks with Mrs. Kirkman at the hospital. He drops off the gift in Sophia's room. The bomb was a decoy. Rossi conducts a cognitive evaluation of Rhonda's father. He remembered passing a house surrounded by police tape. The unsub pretending to be Rhonda's doctor calls her mother telling her to go to the hospital. Rossi and Prentiss recall a house in that area in which eight poisoning victims had been found. The unsub is after the mother, who had accidentally stepped on his floral tribute to his father while taking a picture. Garcia identifies the unsub as Shelby Mattson, who takes the mother to Rhonda's home. The BAU arrives after he has set the bomb in the mother's lap. He threatens to release the trigger and Prentiss tells him to go ahead. JJ shoots Shelby when he runs with his keychain, not the trigger.