Weird dash leak on my Lonestar

[Aleksii]

New to the board here, but here goes:

I've got a 2013 Lonestar and it's accumulating water on the dash .. specifically where the windshield meets the dash, and then leaking along the firewall onto the floor and soaking my floorboards. Doesn't seem to be coming from the windshield itself. I *think* it may be coming in from where the HEPA filter is ? but I've got NO IDEA where the water is actually coming from, and I'm wondering if anyone else has had this problem, and what the best fix for it is.

Personally, I'm thinking clear silicone along the entire truck where the roof meets the cab.

Thoughts?