Movie: Directed by Joss Whedon.
Inciting Event: The entire first half of the First Act sets up the main conflict: Loki’s stealing the Tesseract. But that isn’t the Inciting Event. The Inciting Event doesn’t happen until this conflict begins brushing with the main characters. The First Act turning point/Inciting Event occurs when Natasha is sent to fetch Bruce, which sets up the scenes to follow, in which Fury recruits Cap and Coulson visits Tony.
Thor isn’t introduced in the First Act, but he is referenced, which sets up his appearance later on. Although it’s not usually advisable to introduce important characters so late, it’s a bit of a necessary evil here, since there are so many characters to be gathered. It also helps that Thor was introduced in his own movie previously.
First Plot Point: Cap, Bruce, Natasha, and Fury assemble on the helicarrier, which takes off and cloaks itself. This is an obvious shift out the Normal World of the First Act into the adventure world of the Second Act. This is where most of the characters finally come together, and where they physically shift locations into the primary setting of the main conflict.
First Pinch Point: After Loki allows himself to be captured and Thor shows up, Loki and his alien spear are brought aboard the helicarrier. This is the obvious turning point in the First Half of the Second Act. It isn’t, however, as obvious a Pinch–but we know this is where Loki starts messing with everyone, trying to get them to turn against each other. The emotional pinch in the pacing comes when Tony convinces Cap that Fury is hiding something from them.
Midpoint: After everyone learns SHIELD is weaponizing the Tesseract, a brain-hacked Agent Barton attacks and invades the helicarrier. Bruce loses control and turns into the Hulk. Half of the engines die, and Tony and Cap must put aside their differences to try to repair them.
This is a huge sequence that stretches well into the second half of the story. It marks a decided shift in the characters’ mindsets. Prior to this moment, they are all reacting to Loki and his plans, as they squabble amongst themselves. After this moment, they gain a better understanding of the nature of conflict and what Loki intends to do. They pull together and start taking action as a team.
Second Pinch Point: Loki escapes, killing Agent Coulson (and trying to kill Thor by jettisoning him from the helicarrier). This scene is actually part of the Midpoint sequence, but because the sequence is so long, it extends all the way into the Second Pinch Point. Note that this is something that would rarely, if ever, happen in a book, due the greater length.
Third Plot Point: Loki unleashes his Chitauri army from outer space. The low moment for the characters is more symbolic than anything—as they are confronted with an almost insurmountable wave of opponents.
Climax: The focus of the battle shifts, as the team realizes they must close the portal to prevent any more Chitauri from entering. A previously brain-hacked Eric Selvig wakes up and reveals to Natasha that Loki’s scepter will close the portal. Meanwhile, the World Security Council decides to nuke the Chitauri—and Manhattan. Tony catches the nuke and hurls it into outer space, narrowly escaping through the closing portal.
Climactic Moment: The nuke blows up the Chitauri ships, incapacitating all the remaining Chitauri on Earth.
Resolution: Everyone goes their separate ways—after eating at Schwarma’s.