The concept of a hook does not apply only to
pop songs. In fact, it was invented to describe a crucial element of
journalism, and extended from there to become an important concept in all branches of the publishing world. The hook is the special angle that makes a story catch the reader, the element that makes that story different from all others or so
resonant that it simply must be read. The most common sort of hook is the
human element that forces the reader to identify with the
protagonist through manipulation of
known emotional stimuli.
Take for example the comic book "Birds of Prey", a DC comic set in Gotham City and starring Oracle, Black Canary and various female guests. There are dozens of other monthly comics with female stars, many of them more powerful and dressed in sexier outfits than the Birds of Prey. What makes BOP unique is that one of the heroines, Oracle, is a hacker who has no superpowers whatsoever. In fact, she's physically handicapped, stuck in a wheelchair for life thanks to the Joker, and the only thing she has going for her is her highly developed intelligence.* That's the hook, the unique factor that is supposed to catch the reader's attention and make him (or hopefully her, as BOP is a comic carefully planned to appeal to both sexes equally) say "Wow, I never saw a superhero like that before".
* - I know, someone is bound to mention that Professor Charles Xavier is also crippled, but Professor X has amazing powers of telepathy and a super-powered wheelchair manufactured by aliens. It isn't the same thing at all.