The main character , Humbert Humbert , falls in love , and has sexual relations with a 12-year-old girl nicknamed Lolita .
As Lolita and Humbert drive westward again , Humbert gets the feeling that their car is being tailed and he becomes increasingly paranoid , suspecting that Lolita is conspiring with others in order to escape . She falls ill and must convalesce in a hospital ; Humbert stays in a nearby motel , without Lolita for the first time in years .