Adventurer Harry Wingate is hired by an obsessive gem collector to recover the "Blue Lightning", a dazzling opal in the hands of Irish Republican Army financier Lester McInally, who has created an impenetrable fortress in a small town in the Australian outback. Teaming up with the wife of a private detective who also ran afoul of McInally, and some aboriginal helpers, Wingate prepares for an assualt that will determine who will possess the "Blue Lightning."