From the moment a dramatic situation which contains a grave conflict has been created and has to be resolved one way or the other, the audience begins to guess in what direction the story will develop, accepts the hopes and desires of the main character and, at the same time, begins to realize the abyss in which the hero could crash.
From this starting point - the beginning of the second act - the efforts to solve the predicament (often caused by some kind of offense, wrong-doing, injustice, or error) lead to several sequences of rising action.
Hopes and expectations are created, alternative approaches or directions are weighed, doubts and hesitations are fought, decisions are made and actions are started. The first obstacles are overcome and, in the middle of the second act, things reach a point that looks like a possible solution, either negative or positive (the first culmination).
But the consequences of previous actions, new counteractions of the antagonist, new complications (usually unexpected yet explainable) or new obstacles arise, forcing the characters to exert all their faculties, powers and talents. The audience’s involvement grows higher, too, until, in the last sequence of the second act, where the main culmination is reached.
That is the extreme ulterior point of the protagonist’s drive or defense. He or she has done everything that is in his or her powers. The battle is solved and “descending” action starts with a new tension.