What has Pretty Little Liars showrunner Marlene King and actors Tyler Blackburn (Caleb) and Ashley Benson (Hanna) so serious? We imagine filming one of Hanna and Caleb’s final scenes together will do that to a person...

“Serious convo @imarleneking @longhaired_child,” Ash posted on Instagram, along with this picture of herself, Marlene, and Tyler on the PLL set (specifically, a Rosewood street). In the snapshot, they are all standing close together, and Marlene and Tyler have their arms around one another in an aww-worthy moment.

“We were hard at work discussing character motivations. @AshBenzo @tylerjblackburn,” Marlene responded in a tweet. Seriously, Marlene, what is the character motivation for Caleb leaving Rosewood for Ravenswood? We need to know!

We’re guessing this is a pretty intense scene, given that the PLL cast and crew are hard at work filming the Season 4 summer finale. In PLL finales, almost every scene is intense!

Technically, Caleb doesn’t skedaddle until the Halloween episode that comes after the finale, but as that has already been filmed, this is not only potentially one of the last scenes Haleb will have together on screen, but it could be one of the very last scenes Ash and Tyler will film together (at least for awhile). Yeah, we’re looking pretty serious right about now, too.

What do you think is going down in this scene? What do you think Caleb’s reasons for leaving Rosewood will be? Sound off in the comments below!

Catch the next episode of Pretty Little Liars on Tuesday, July 16, 2013 at 8 p.m. ET/PT on ABC Family.