Two equally weighted storylines running in parallel, influencing each other — not main plot plus subplot. Examples: Godard films, *Babel*, *Crash*.
Telling two stories simultaneously without one dominating the other is the core principle, and it demands radical decisions from the director in dramaturgy and editing. Unlike a classic main plot with a subplot, both strands work at eye level, intertwining through theme, character, or coincidence, and the viewer never truly knows who the "main character" is. This creates tension through disorientation – intentionally.
On set, this means concretely: you plan two complete locations, two lighting moods, possibly two image composition logics. The lighting and camera language can run in parallel or deliberately contrast. Godard did this radically – two couples in "Bande à part," two perspectives in "Vivre sa vie," both stories equally important, equal screen time. The viewer is left hanging, wondering which strand will "win." In editing, then, comes the craft: editing rhythm becomes a level of meaning. Equal scene blocks signal balance; more frequent changes create nervousness; longer stays in one story suggest (falsely) importance.
Practitioner's trap: Many directors slip into a hidden hierarchy – one story gets better actors, more time in the third act, more emotional music. Immediately, it's no longer a dual structure, but a disguised main plot. "Crash" or "Babel" only work because the director and editor remain consistent: equal scene weights, equal emotional arcs, editing pace that signals "everything is equally relevant." This is more strenuous to write and edit than it looks.
The resolution is delicate. Classic Hollywood requires convergence – all strands meet at the end. Dual structures can do this, but don't have to. Godard often lets them end in parallel, unconnected. This is unsettling – and that's the intention. For you as a cinematographer, this means clarifying with the director whether both worlds should be visually separate or blurred in color, light, and depth of field. This is not a detail, but a structural statement.