Definition: In this task, five ordered key facts are given. All the given facts are expressed in natural language. Your job is to generate a story 100 to 1000 words long, that includes all the facts given as input in their order of appearance while expanding upon them to produce a broader, yet coherent, narrative.
Input: Fact1: Old Man When decides to investigate reportedly lands, Fact2: Sam are defeated by agents, Fact3: aliens reproduce by division soon controlling not only most of population of infested area but also military personnel sent to area to fight them, Fact4: slugs whom n't possess surviving people, Fact5: boy suffered from encephalitis

When a flying saucer reportedly lands in rural Iowa, The Old Man who runs a secret branch of the CIA, decides to investigate. He goes in person, accompanied by agents Sam who is the son of The Old Man and Jarvis, as well as Dr. Mary Sefton, a NASA specialist in alien biology. They find that aliens have indeed landed and are planning to use their mindcontrol powers to take over our planet. The aliens are sluglike creatures, and they are attaching themselves to peoples backs, taking control of their victims nervous systems, and manipulating those people as puppets. The slugs spread steadily, and soon attack one of the agents, Sam. Controlling Sam, aliens almost possess the president, too, but are defeated by the agents. Agents then learn they can remove a slug by an electric shock, and free Sam from the possession of a slug. It is soon found out all slugs share a common consciousness, a sort of a group mind. The aliens quickly reproduce by division, soon controlling not only most of the population of the infested area, but also military personnel sent to the area to fight them. As agents learn where the aliens hive is located, they attempt to sneak in, and release Mary, whom aliens captured earlier. Together, they find surviving people whom slugs couldnt possess. They take one of them, a boy, with them, leaving the hive. It is soon found out the boy suffered from encephalitis in the past, and that apparently was the reason a slug couldnt possess him. A biological warfare is adopted, and seemingly all parasites die. During a later inspection of a hive, The Old Man is attacked by the last healthy slug. In a fight on a helicopter, Sam destroys the parasite attached to the body of his father.