- A B-story is a secondary storyline beside the main A-story.
- It often carries the theme or a relationship arc.
- It provides contrast, depth, and pacing relief.
- It usually intersects or informs the A-story.
- The term is common in screenwriting and structure frameworks.
A B-story is a secondary storyline that runs alongside the main plot (the A-story). It frequently carries the theme or a key relationship — in many frameworks, the B-story is where the protagonist learns the lesson that lets them resolve the A-story. Beyond theme, B-stories add depth, provide contrast and pacing relief from the main plot, and usually intersect with or inform the A-story by the end. The term is common in screenwriting and structure models like Save the Cat.
Chapter i·Why it matters
Understanding the B-story clarifies how subplots function structurally — not as filler, but as a deliberate secondary thread that often delivers the theme and supports the main plot. Knowing how A and B stories interweave helps writers build richer, more thematically resonant books and diagnose subplots that wander or fail to connect. It is a key concept for structuring multi-threaded stories where the secondary line strengthens rather than distracts from the main one.
Chapter ii·What to include
- A secondary storyline beside the A-story.
- Theme or relationship arc often carried here.
- Contrast, depth, and pacing relief.
- Intersection with the A-story.
- Its role in structure frameworks.
- A purposeful secondary thread, not filler.
Chapter iii·Example
In a thriller, the A-story is the protagonist hunting a killer; the B-story is her repairing her relationship with her estranged daughter. The B-story carries the theme of trust — and the trust she relearns there is what lets her resolve the A-story. The secondary thread deepens and supports the main plot.
Chapter iv·Related questions
WriteLoom's Plan studio maps your A and B stories together, so secondary threads carry theme and support the main plot.
See the Plan studio