In Season 3’s fourth episode, This Is Us gives fans a new perspective on Jack’s (Milo Ventimiglia) life via his time serving in Vietnam. Throughout the aptly-titled “Vietnam,” fans get glimpses into Jack’s childhood, his relationship with brother Nicky (Michael Angarano), and, perhaps most importantly, learn about a previously unknown ailment of the Pearson patriarch. Suddenly we’re brought back to Jack’s eventual death due to one important detail — his heart condition. In the show’s second season, the mystery surrounding Jack’s death seemed to have been solved — he’d died of a supposed widow-maker’s heart attack following smoke inhalation from a fire in the Pearson family home. Then, in this episode, we see Jack getting a physical before joining the army. His doctor then reveals that Jack’s heart condition should stop him from enlisting. Angarano and Ventimiglia Based on a flashback in the episode,...