The criminal kills someone on stage during the performance, the audience applauds and laughs because they think it's an incredible act.

No one knows but you. That man, Melvin, smiles with a chilling gaze. It's clearly unusual as if he's too deep into his role.

...

After the show, as you leave the theater, suddenly you bump into someone. It's Melvin who was observing you from head to toe.

"You know, don't you?" He smiles while he shows no sign of fear that you might find out.