Franklin Blake is probably the closest thing to a hero in this novel – he's the guy who gets the girl and, although far from perfect, he's by and large an admirable character.
If Franklin Blake is the hero, Rachel's definitely the heroine. She isn't present for a lot of the story, though, because she's not on speaking terms with Franklin for most of the novel. But we hear plenty about her from other characters, and it's almost all good.