The detective/thiller genres have a basic formula: There’s a killer on the loose. Someone from the police force, or someone acting like the police, finds the killer and puts that person in jail, with maybe a few love problems on the side.

The Dexter Books by Jeff Lindsay are similar, except for a couple details: the main character does work for the police and is very good at catching killers, and he does have a few troubles with his love life. The difference is, when he finds the murderers, he kills them.

The first book, “Darkly Dreaming Dexter,” revolves around a serial killer who has his eye on Dexter and seems to know his dark secret. Dexter works with his sister, Deborah, a cop on the force, to find the killer, for whom Dexter has great respect.

The second book in the series, “Dearly Devoted Dexter,” deals with more graphic scenes with a very disturbed and creative killer. Dexter seems to be on the brink of discovery because Sergeant Doakes, the only cop on the force that even suspects Dexter of anything, comes close to finding the dark secret.

The third, and most recent book, “Dexter in the Dark,” is very different from the first two, which are in a straight forward manner and basically list events with very little depth and are very quick reads. It delves into his mind and dives straight into the metaphysical, and seems to swim around there on an extended vacation. While it was interesting, committed fans of the first two won’t be impressed with the most recent book if they wanted more of the same.

The Showtime series, “Dexter,” was based on the first two books, and while the main character is the same and some of the plot stays consistent, the transition from paper to screen changed the stories and character developments majorly. The relationships between the characters are more developed in the show. Dexter’s fiance’s children are almost invisible in the show, while the books have them very involved in Dexter’s life. The first season roughly follows the first book, but the second season has basically nothing to do with the book.

It may seem odd to call the first two books light reads with all the violence involved, but they don’t go into very much depth and can be read quickly. The third book forces you to slow down because of all the philosophy threaded throughout the almost nonexistent plot. The climax and resolution occur within four pages, and it really seems like a weak ending. “Dexter” is one of my favorite TV shows, but it’s not my favorite thing to read.

Season 3 premiers Sunday, Sept. 28 at 9 p.m. on Showtime. “Dexter by Design,” the fourth book in the series, is said to come out Feb. 2009.