Boo is a 2005 American horror film directed by Anthony C. Ferrante. Plot Jessie Holden is invited by her boyfriend, Kevin, and two friends, Freddy and Marie, to spend one Halloween night at Santa Mira Hospital, abandoned years ago due to a fire. Their friend, Emmett, is preparing the props to scare Jessie when he and his dog, Dutchess, are attacked by a ghost. Meanwhile, Allan is searching for his sister, Meg, who went missing with her friend, Caitlin, in the hospital a few days ago. His father's old friend, former actor-turned-cop Arlo Ray Baines, initially refuses his plea to accompany him to the hospital, but changes his mind and trails him anyway. Allan finds Dutchess horribly mutilated, but she suddenly rises up and attacks him until he shoots and blows her to bits. Upon entering the third floor, he reunites with Meg, who says that she got separated from Caitlin. Arriving at the hospital, the four friends begin searching for Emmett. When they are alone, Kevin cheats on Jessie by having sex with Marie. Meanwhile, Jessie, who is revealed to be spiritually aware, tells Freddy the story of her late mother, who died due to disease years ago but is still calling her every Halloween. The two stumble upon a terrified Emmett in the locker room. When the five meet up, Emmett suddenly begins attacking them. Allan and Meg arrive in time and Meg uses Allan's gun to shoot Emmett to bits. She tells the group that everyone who die in the hospital are reanimated; Emmett and Dutchess are among them. A paranoid Kevin, suspecting that Marie is becoming a ghost, grabs Allan's gun and shoots her dead. Since Meg refuses to use the elevator, the group split up, with Jessie, Kevin, and Freddy taking Marie's body to the elevator and Allan and Meg using the stairs. The former three are transported to the third floor, where Jessie has a series of premonitions involving a child murderer named Jacob. Jacob was committed to the hospital's third floor that was specifically reserved for mental patients. Despite this, he managed to murder a little girl in the hospital's premises anyway. When he tried to run away by burning the hospital as distraction, Nurse Russell threw away the door keys, trapping both of them in the fire. Jacob has been killing and reanimating people in the hospital so he can possess them,