Question: does she kill glenn in the book of henry

Answer: No, Susan slips away from the talent show and puts the plan into motion. As she is about to pull the trigger, however, she realizes that Henry's plan, though ingenious, is the construct of a child, and that she must act as an adult. She immediately confronts Glenn and tells him that she is going to expose him for what he has done to Christina. Glenn replies that everyone will believe him, not her, and he tells her that he is going to call his police chief to come and bring her in. At the same time, affected by Christina's dance performance at the talent show, Principal Wilder decides to follow through on the abuse accusation and contacts the authorities. Glenn returns home, calls his relative at Social Services, and learns that an investigation is being opened into his abuse of Christina. As the police arrive at his house, Glenn kills himself. Susan legally adopts Christina as her daughter. She also finishes writing one of her children's books, as Henry had urged her to do.