inciting incident, catalytic event, call to adventure, point of attack
a plot point in the [middle of the] first act which, directly or otherwise, disturbs the life routine(s) of one or more of the characters - the future protagonist(s) - and sets them in pursuit of an objective [against obstacles which create uncertainty and suspense] for the whole of the duration of the unit of drama (a scene, a sequence, an episode or the work as a whole). (Lavandier, 2005) The inciting incident doesn't have to directly relate to the protagonist. It can be an incident (eg murder, plane hijacking, or car accident) that the protagonist is not involved in and knows nothing about, but at some point in the first act it has ramifications that impact and influence the actions the protagonist will take throughout the story. The inciting incident is a major aspect of the setup of the first act. (Marks, 2009)