Nabokov's Lolita is a real professor's book because it is loaded with clever wordplay and references to other works and writers such as Poe, Shakespeare, and Merrimee. Proffer's book goes into these things extensively. He seems fascinated in particular with the trail of clues, both legitimate and false, which Nabokov lays down for the sophisticated reader and which hint at the story's ultimate disposition and the identity of the man who helped get her out of Humbert's clutches. It is not a mystery in the traditional sense of having several suspects and a bunch of clues leading in different directions; Nabokov's mystery exists in the writing but not in the story. Only a very knowledgable reader would pick up on the clues (I didn't). Nabokov is the kind of writer who enjoys playing cat and mouse games with his readers by manipulating them this way and that. He is also a rather cold writer who seems emotionally disassociated from his characters, or who enjoys portraying characters who are contemptible or pathetic individuals.
Proffer's book focuses on 3 things: literary allusions, the hints and clues leading up to the revealing of Quilty (Humbert's nemesis), and the poetic aspects of the prose, things like alliteration and assonance, and this section contains some unnecessarily exhaustive lists of phrases which are, in an odd way, interesting to read kind of like looking at a series of square centimeter sized sections of a painting. Lolita is a complicated book, and it is good to have a little guidance to help get the most from it. I am glad that I picked this up to help me in my reading.