Chamberlain's most striking claim: 99 percent of first-time screenwriters don't write stories — they write situations. The distinction isn't about quality or effort. It's structural. A situation presents a character dealing with problems: a cop chases a killer, a couple navigates a long-distance relationship, a teenager survives high school. Things happen, conflict exists, there may even be a resolution. But there's no mechanism forcing the character to confront their specific flaw. A story, by contrast, has a structural trap built into it — the 'catch' — that specifically tests the protagonist's weakness. The external problem and the internal flaw are mechanically linked so that solving one requires confronting the other. Without that link, the character can solve their problems without changing.
Check Your Script
State your protagonist's central flaw. Now state the external problem they face. Is there a structural mechanism — not just a thematic parallel — that forces solving the external problem to require confronting the flaw? If the character can resolve the plot without personal transformation, you have a situation.