In Miss Peregrine's Home for Peculiar Children by Ransom Riggs, there are multiple children (and some adults) that have very strange powers and abilities. The main character Jacob does not believe he has any sort of supernatural ability himself, especially after seeing what all of the other children in Miss Peregrine's home can do.
In chapters eight and nine of the book, though, Jacob discovers that he does have a gift after all: he can see the monsters like the ones that killed his grandfather in the woods behind his house at the beginning of the novel. This is crucial to the story: it is why he was able to see the creatures when no one else saw them. He had known all along that it had not been wild animals that killed hid grandfather, just as he had known he wasn't losing his mind like others implied.
It turns out that other peculiar children, like Emma, can see the monsters too, just not as clearly as he can. "Only their shadows," she says, when he asks if she can see them at all, "which is why they hunt mainly at night."
The monsters must hunt under the cover of darkness so that they can't be seen by people who could stop them from carrying out their evil deeds, which is why they only hunt at night.