Mike gets a call about his new work, the detective, being late for first draft. He later comes across his ex on the street, which sends him into an alcohol fueled writing session. He leans back on his chair, falls and wakes up in his own story. He is stuck with no way out with his ex and her new guy. Quickly he realizes that the only way out is to play along and leave the plot as untouched as possible.
A couple of drinks and a gorgeous femme fatale, Marilyn, later, this solution has flown out of the window. After the two murders Mike knew about, there are more and more dead bodies piling on the already big stack, and Mike stumbles through the story accidentally gathering more and more information about his story he never even knew about.
The mystery surrounding who the murderer is never stops right until the end. Mike didn't finish his novel, so he doesn't know who the murderer is. All of this leads to the conclusion, one he would have never realized if it wasn't for his participation in the story.