The Boy from Andromeda (1991)

On a holiday to Tarawera Volcano, Jenny finds a strange fragment of metal -part of the mysterious "Fire Key". Unbeknownst to her, just by touching it, she awakens someone who had been sleeping for a hundred years. Then Jenny discovers that local teenagers Tessa and Lloyd, each own pieces of the key. Once all three parts are fitted together, the trio are plunged into a terrifying set of events...