Level 26

Level 26 is a digital horror novel series by Anthony E. Zuiker and Duane Swierczynski.

[2][3] Law enforcement personnel quantify evil and murderousness on a scale of 1 to 25, with naive opportunists at Level 1 and organized, premeditated torture-murderers at Level 25.

An elite investigative unit, headed by reluctant operative Steve Dark, must track down the killer who is forming a new category.

As a result of the events in the previous book, Steve Dark has crossed the line and considers himself no longer bound by the law in his pursuit of "level 26" killers.

Steve Dark faces a killer named Labyrinth, who uses riddles, puzzles, and wordplay to announce his targets ahead of time.