If you're worried about plot spoilers, you can rest assured knowing the game won't ruin the movie, especially since you're only playing through one large level and a bit of story that, as far as we can tell, isn't actually a part of the film. You'll actually be taking on the role of Thanos in the DLC, controlling his army as you invade Attilan, the home of Black Bolt and his Inhumans. You'll fight all over Attilan and eventually make your way to Black Bolt's own throne room.