The climax marks the "highest point" of a story, the place where the tension in the plot is at its thickest. In Neil Gaiman's Coraline (2002), the thrilling sequence leading to Coraline’s escape from the other mother's world marks the climax. Apart from being the story's tensest point, this sequence is also the climax because it shows Coraline apply the lessons learnt from her stay in the other mother's world to her do-or-die predicament.
Coraline has already defeated the other mother once by finding the souls of the three children trapped by her. She has overcome her fears and learnt a new resourcefulness. But she is still stuck in the world of the other mother and has yet to rescue her parents. In rescuing her parents and escaping from the other world, Coraline will show the reader the new, resurrected self she has discovered while finding the three children's souls.
The third reason the escape is the story's climax is that we are still uncertain about Coraline's fate. Will she be able to make it out? Or will she, her parents, and the lost, ghost-children remain trapped forever? Typically, a protagonist's fate is unknown till the climax; once the reader can predict this fate, the action begins to fall away.
Coraline knows escaping is tricky, because the other mother does not intend to keep her promise of letting Coraline go if she finds the three souls. But Coraline has some help: the protective stone-with-the hole from the real Miss Spink and the real cat. Therefore, she bravely steps into the other mother's drawing room, where she knows the exact spot her parents have been hidden in plain sight. Coraline cannot let the other mother know she knows, so she pretends otherwise:
"I know where they have to be. You've hidden them in the passageway between the houses, haven't you?..."
The other mother remained statue still, but a hint of a smile crept back onto her face. "Oh, they are, are they?"
Here we can see Coraline exploit the other mother's love for games and tricks. She knows the other mother won't be able to resist letting Coraline peek into the passage, so that she can gloat when Coraline discovers her parents are not there. This shows the resourcefulness Coraline has learnt through her stay in the other mother's world.
As the other mother slowly unlocks the door to the passage, Coraline begins to edge toward the mantelpiece where she had earlier glimpsed a snow-globe. She knows the two tiny figures inside the globe are her parents. Meanwhile, the other mother is too fixated on her triumph to notice Coraline's movements.
"There," (the other mother) said…The expression of delight on her face was a very bad thing to see. "You're wrong! You don't know where your parents are, do you? They aren't here….Now… you're going to stay here for ever and always."
It is at this point that Coraline throws the black cat at the other mother's head, reaches for the snow-globe on the mantelpiece, thrusts it deep into the pocket of her dressing gown, and makes a run for the passage. The other mother is temporarily disarmed, trying to rid herself of the flailing, biting cat.
The cat does its job well, clawing the other mother, till a black, tarry substance unlike blood begins to gush out of her skin. "Leave her," Coraline shouts to the cat and steps into the passage. The cat joins her and Coraline begins to pull the heavy door closed. It take great effort, but the souls of the three children, as well as the shadow selves of her parents, give her emotional strength and Coraline manages to shut the door.
She has safely seen everyone out of the other mother's world. The reader lets out a sigh of relief at this point. The story's tensest point is resolved, and though Coraline has another, smaller battle left to fight, we now know she is going to be absolutely fine in the end. Thus, the action begins to fall away. Coraline has her wits about her and has also gained a renewed appreciation for the ordinariness of the real world and her real parents. This world is worth fighting for, and Coraline will now fight hard for it, whenever required.