Todorov's Narrative theory:

Stage 1 - The state of equilibrium is defined

Stage 2 - Disruption to equilibrium by action or crisis

Stage 3 - Characters recognise problems and set goals to fix them

Stage 4 - Characters try to fix problems but there are obstacles

Stage 5 - Equilibrium is re-instated, problem solved, conclusion

For film trailers, stage 5 would not be applicable as the ending is rarely given away in a film trailer.