Young couple goes on van tour of US, boy comes back with van - no girl

Possibly, but just sort of laying ideas out, and when your brainstorming, sometimes things are open to interpretation, or maybe not a lock tight understanding.

How do you see it?
The only question I’m really concerned with is how much/little did his parents know - I really don’t care how he died (unless his parents did it — like some Of Mice and Men sorta deal)