Can You Figure Out the Mystery Inside This Remarkable Ad About High School Love?

Amazing Ad from Sandy Hook Promise which goes to show sometimes the underlying problem isn't right in front of you.
Here's a pretty amazing ad from BBDO New York, with a mystery at its core.  At the outset, we meet Evan, a high school kid who can't wait for summer break. He's so bored that he begins etching words into a table in the library.