Given the question: Build a movie plot around this: Who discovers Mike's exploits? Mike's girlfriend discovers Mike's exploits.
The answer is:
HOW TO BE A SERIAL KILLER is the story of Mike Wilson, a charismatic, educated, and articulate young man who has found his life's purpose in exterminating people. Mike is determined to spread his message about the joy of serial killing and recruits a lost soul named Bart to be his pupil. Mike leads Bart through the ethics of serial killing as well as teaching him various lessons in disposing corpses, balancing work and play, methods of killing, and many many more. Mike and Barts curriculum is interrupted when Mikes girlfriend discovers what's beneath her boyfriend's charming exterior and Mike and Bart must kill their way out of being discovered by the cops.