OK, here's a hypothetical scenario: Let's say that one day I decided to write an action-adventure book. The book is set in the UK featuring a female lead and her two companions. One of them hears of a legend that there was a map written on the back of the Magna Carta that, if decoded, would reveal a shocking twist of evidence to that historical moment in British history. The female lead then discovers, to her horror, that a bunch of crooks also heard of that legend and are going after the Magna Carta so she must go after it first before they do. So begins a chase throughout the UK where she and her companions must keep one step ahead of the crooks as she decodes the Magna Carta, which will lead them to a great find that would change how people viewed King John forever. For those who watched the first National Treasure, this plot sounds eerily familiar. Now let's suppose that I never watched that movie, I had no idea it existed. The setting and characters are different, but the basic plot structure is still the same. Map on the back of the Magna Carta, wild chase throughout the UK, huge find at the end and the crooks go to jail. The reason I ask is because of this: I heard once that the author of The Hunger Games had unknowingly plagiarized an old Japanese film with the same plotline (corrupt government forces kids to fight to the death) and she swore up and down she wasn't even aware of the film. Did she, though unintentionally, plagiarize? I've also been told that even if the plot 'sounds' like the plot of another media, what matters is my own take on it. So I'm a bit confused on that matter. Would this hypothetical book still be ripping off of National Treasure even though I (a) had a different set of characters and setting and (b) never heard of this film in this scenario? Thoughts?