The next time you watch any two hour move, time your watch to the one hour mark. When you hit the one hour mark, notice how everything seems to be going well for your hero. Then notice immediately afterwards how everything starts to fall apart.
In “The Interview,” the hero is a Hollywood gossip talk show host who goes to North Korea to interview Kim Jong-Un. During the first hour, the hero gets to know Kim Jong-Un and become friends with him. During the second hour, the hero realizes that Kim Jong-Un is an unstable nut with nuclear weapons and doesn’t care about killing people for his own needs. Then the hero learns that a grocery store supposedly showing how well fed the North Korean people are is actually a fake. Things fall apart even more when the hero departs from the script and starts asking Kim Jong-Un questions about why he’s starving his people.
Break any movie in half and you’ll find the same pattern of everything going well for the hero right up until the mid-point where everything suddenly falls apart. In “Avatar,” the hero has finally made love to the alien girl at the halfway point. Then things start to fall apart when the hero wakes up to see bulldozers plowing down the forest, which causes him to jump up and attack the bulldozer. His attack gets caught on video, which causes more trouble for him. Then the villain discovers the hero’s video of him getting discouraged with the way the humans are treating the aliens.
In “WALL-E,” the halfway point is where WALL-E finally dances with Eve in space after rescuing the plant. When they go back to the spaceship, the villain tries to destroy the plant along with WALL-E and Eve in the process.
The halfway point is where the story shifts. In the first half, the hero may have been struggling but eventually achieves an apparent or false victory. Then the second half is where everything falls apart for the hero and improves for the villain. In the first half, the hero almost achieves a goal. In the second half, the villain almost achieves a goal. Then in the climax, the hero and villain collide so we can see who wins out in the end.
Divide any movie in half and you can see this structure. Now that you recognize this halfway point in every story, use it for your own screenplay.