I think you have to play the game to understand the movie completley and be able to enjoy it. Reading a summary is ok, but you'll have to keep in mind many things that was said in the summary and distract you from the movie. When you play the game you become more familiar with the characters and know all their little quirks and such without having to forcibly remember them. Since you spent a lot of time around these quirks in the game you know them by heart and don't need to remind yourself, so to speak. As said before, AC is not a stand alone movie. It leaves most of the char development and situation set-up to the game. So playing the game helps a lot. You can still enjoy the movie but you won't understand why this is so and why that is such and so on. You'll be a little lost. Unless it's a very good summary and could be a short story, go play the game. Then see the movie. That's my advice.