Today was the NBC’s Drama Panel at the Television Critics Assoc. summer press tour, and co-showrunner Elizabeth Berger said lightness will overtake the darkness in This Is Us‘ upcoming third season. “We felt like at the end of Season 2, our family had grieved and processed [Jack’s death].”

The Season 3 premiere — which is set to air on Tuesday, Sept. 25 (9/8c, NBC) — once again centers on the Big 3’s big day. “We are picking up with [Randall, Kate and Kevin] turning 38,” shared co-showrunner Isaac Aptaker, before adding, “Our storylines are going to catch up to all of those [flash-forward scenes from the Season 2 finale] over the course of this year.”

Aptaker also confirmed that “we are going to be spending a lot of time in Vietnam” exploring Jack’s war-torn origin story. Added Berger: “There’s something very freeing about being past the mystery of Jack’s death and moving into this new chapter and being able to tell a completely different kind of story. To be all of a sudden [writing] about the Vietnam War is very special and different.”