Double Narrative Flashback
If you're writing what I call a double narrative flashback film (that is, a film like Slumdog Millionaire or Shine or Remains of the Day, where you've got a complete narrative in the past, and a narrative in the present, and you're jumping to and fro) think of it as two films and plan both as three act structures (although the story in the present will probably be very short). Flashbacks do not occur randomly, neither is their content random. The content of the opening scenes isn't random either.
Put simply, you'll be jumping between stories on cliffhangers but where you start the film and the jumping and the logic of the jumps can differ between forms. If you don't get all of that right you're cactus, so see The 21st Centrury Screenplay for details on all of this.
Bear in mind that the story that always gives writers the most trouble in double narrative is the story in the present - because it can so easily become redundant. The reason is that you're not particularly interested in it. The story that interests you is the story in the past, but unless you write a vivid (albeit) short 'detective story' in the present about someone trying to find out answers regarding the motivation of an enigmatic person (dead or alive), there is no real point is creating a story in the present and it can become deathly boring.
Put simply, you'll be jumping between stories on cliffhangers but where you start the film and the jumping and the logic of the jumps can differ between forms. If you don't get all of that right you're cactus, so see The 21st Centrury Screenplay for details on all of this.
Bear in mind that the story that always gives writers the most trouble in double narrative is the story in the present - because it can so easily become redundant. The reason is that you're not particularly interested in it. The story that interests you is the story in the past, but unless you write a vivid (albeit) short 'detective story' in the present about someone trying to find out answers regarding the motivation of an enigmatic person (dead or alive), there is no real point is creating a story in the present and it can become deathly boring.