Narrative - structure, formulas and devices

Continuity Editing
The clear establishment of 'cause and effect' plotting which establishes character motivates and helps tell an interesting story which proceeds logically and steadily.

Enigmas
This refers to a puzzle something mysterious or unexplainable, or a riddle or difficult problem.
In thrillers this is commonly something which the protagonist has to try and find out or solve before the narrative is resolved and the film finishes.

Red herrings
A red herring is the name given to a device which intends to divert the audience from the truth or an item of significance.
Can work with other devices (enigmas) to create suspense.
E.g. in SAW two characters spend time imprisoned in a room in which a third character lies dead. throughout the film, both characters appear to be guilty of a series of murders, until it is discovered at the end that the third person in the room is not actually dead but is in fact the killer.

Cliff hanger
Sometimes, although not always used.
Often feature a main character in a precarious or difficult dilemma or confronted with a shocking revelation.
This can entice the audience to keep watching in order to se how the situation resolve itself.