When the often fearful eleven-year-old Tom (Milo Parker - Mr. Holmes) discovers a slimy green ghost in his cellar called Hugo, he is understandably afraid. However, Tom soon realises that Hugo, who is an ASG (Averagely Spooky Ghost), is not only completely harmless but also desperately in need of his help. He has been banished from his haunted house by a dangerous AIG (Ancient Ice Ghost) who has moved in and is spreading an arctic cold over the entire town in the middle of summer! To help get rid of this AIG, Tom and Hugo enlist the services of a professional Ghosthunter, Hetty Cuminseed, who has just lost her job at the CGI (The Central Ghosthunting Institute). Hetty doesn‘t like children or ghosts very much but Tom and Hugo convince her to teach them the basics of ghosthunting. The three become an unlikely team – only with friendship, courage and self–confidence can they overcome their adversary and save the town from the AIG. Will the unconventional trio overcome their differences, and manage to defeat the evil Ancient Ice Ghost, and save the town from an icy end?