Phenomena is a 1985 Italian horror film directed by Dario Argento and starring Jennifer Connelly, Daria Nicolodi, and Donald Pleasence. Its plot focuses on a young girl at a remote Swiss boarding school who discovers she has psychic powers that allow her to communicate with insects, and uses them to pursue a serial killer who is butchering young women at and around the school.
After missing the bus in the Swiss countryside, a tourist, Vera Brandt Fiore Argento, tries looking for help. She comes across a home, and upon entering, she is attacked by an unknown stranger, who then proceeds to chase and behead her. Eight months later, Jennifer Corvino Jennifer Connelly, arrives at the Swiss Richard Wagner Academy for Girls, chaperoned by Frau Brckner Daria Nicolodi, who places her with roommate Sophie Federica Mastroianni. While sleepwalking through the academy and out onto the roof, Jennifer witnesses a student being murdered. She awakens and falls, fleeing and eventually becoming lost in the woods. Forensic entomologist John McGregor Donald Pleasences chimpanzee attendant Inga Tanga finds her and leads her to him. Witnessing her apparent interaction with his insects, McGregor comes to believe she has a special gift for telepathy with them. Inspector Rudolf Geiger Patrick Bauchau is also in the case alongside McGregor. Back at the academy, the headmistress has Jennifer medically tested via EEG for her sleepwalking. The procedure makes Jennifer uneasy when she gets brief visions of the previous nights events. The headmistress then has Sophie look after Jennifer in case she sleepwalks again.Following an illicit tryst the same night, Sophie is murdered. Jennifer sleepwalks again, and when she goes outside, a firefly leads her to a maggotinfested glove. The next day, she shows this to McGregor, who then tells her about the Great Sarcophagus fly, which is drawn to decaying human flesh. He explains that the maggots Jennifer found are actually the larvae of this insect and theorises that the larvaes presence on the glove indicates that the killer has been keeping his victims close to him postmortem, unintentionally collecting the larvae on himself whilst physically interacting with the victims. He soberly warns Jennifer that they are dealing with a psychopath, based upon the killers evident desire to retain his headless victims until they rot to bon
Source: Wikipedia