Koontz’s openings always seem to draw me in, like in his book “Velocity”. The second line of the book is: Henry had been killed by a garden gnome.
I enjoy seeing how he weaves a sentence like that into his book’s story. Odd sentences like that seem to hook me.
My understanding is that the hook must be related to the book when it draws you in so that as a reader you aren’t let down by the sentences that follow. So of course it must be tied to the plot in some way, no matter how odd.
Some days I walk through the library, pulling books off the shelf at random and reading their first pages to get an idea of what “hooks” work and what don’t in making me want to read the story. And sometimes the more subtle ones will draw me in before the shocking ones.