Maleficent, one of my favs, is an example of giving in to your darkness during a crisis.
All hope is lost. Your protagonist has done everything she possibly could to save her world. She's hit rock bottom, she's out of ideas, nothing can be done. She's endured torture and pain long enough, and that second plot point has her swirling in despair. It's over, right? The End. No point in reading (or writing) anymore. Just let her be the Maleficent she was destined to be...
If that's what's probably going through your protagonist's head (or maybe even your head), then congratulations! You've reached the darkest moment of the story. The darkest moment, often referred to as the black moment, is the crisis of your story and is defined by "The Five D's."
The Five D's:
Dilemma: It's over. There's nothing she can do. It's all fallen to pieces.
Desperation: You know the phrase, desperate times call for desperate measures. Here, she'll do anything, and she'll probably mess things up even further here.
Despair: She surrenders to her fate.
Deconstruction: With surrender comes a calm. She's forced to think about the situation, figure out what her needs and options are, and what she concludes with is usually centered around her values that have been present throughout the story.
Decision: She's had her eureka! moment. She will make a sacrifice, knowing what needs to be kept and what she can afford to lose, and figures out a course of action to resolve the conflict.
Don't forget, Maleficent was one of the good fairies.
The darkest moment is when your protagonist grows the most. She has to. In her surrender in the despair moment, it's kind of a false surrender. She's letting go of what she's been holding on to, and in some cosmic narrative way (often portrayed with lots of metaphor), she comes to understand what's really important to her. With her back up against the wall, she bounces back with the confidence and resolve she needs to drive the story to the resolution, triggering the beginning of Act Three. She sustains this newfound strength and wisdom to the end. She's a changed person.
The same thing happens in real life, and this is why this moment is so important. Think about a time in your life when you had your back up against the wall. Did you think you were going to make it out? Maybe, but you were far more doubtful than you were hopeful. The darkness was crushing you, and you couldn't find the light that helped you shine all along.
That shining light is the resolution. And that light is the photosynthesis you and your protagonist used to grow, and that marks the second point where you and her will never be the same person again.
I told you metaphor was important, didn't I?
Prior to the darkest moment, your protagonist made the decision to become proactive. She's no longer the hunted, she's the hunter. That's cool and all, but eventually, she fails. Just like we do when we decide to go after something we want--when we want to make that change in our lives.
This is the beginning of her crisis. This was the beginning of yours. Are you on your way to being a Maleficent or a Princess Aurora?
Think back to why you failed. It probably has so much to do with your fatal flaw. It has everything to do with your protagonist's fatal flaw. After the crisis has begun, something even worse happens, pinning you/your protagonist against the wall. This could be the death of a loved one, a mistake in a magic spell, the unexpected defeat in battle (again, all real life stuff). But, new information helps the protagonist understand their flaw. This new understanding is what guides you and your protagonist to making the right decision at the second plot point, which initiates the third act of the novel.
Your story can go one of two ways, and it all depends on you(r protagonist)
For clarity's sake: the crisis is not the climax. That comes in the third act. It just feels like a climax. It feels like the end of the world, but it's really not. Keep that in mind next time you're trying to identify crisis vs. climax. The climax always precedes the denouement.
So, what will you(r) protagonist do when she's in her darkest moment?