In October 1993, 19-year-old college student Brian Sullivan checked into a hotel room in Portland, Maine. Days later, he was found dead inside the door locked, the chain secured from the inside.

There were no signs of forced entry. No clear evidence of struggle. And no definitive explanation for how events unfolded behind that closed door.

Was it suicide? An accident? Or something investigators missed?

In this episode, we examine the strange details of the scene, the unanswered forensic questions, and why the mystery of that locked hotel room continues to unsettle those who revisit it.