SPOILER ALERT: This story contains details about This is Us’ fall finale episode “The Beginning is the End is the Beginning.”

This Is Us served one of its signature jaw-dropping twists in the final minutes of the Season 3 fall finale tonight, and it involved Jack Pearson’s troublemaker younger brother Nicky. Long presumed dead, he turned out to have survived the Vietnam War and outlived his hero older brother. In a bombshell development, Nicky was briefly seen in present day. Shown mostly in silhouette against a bright window, the Big Three’s uncle was played by veteran actor Griffin Dunne.

We can now reveal that Dunne is joining This Is Us in a the recurring the role of a present-day Nicky Pearson. (The younger version of the character is played by Michael Angarano).

In a post-mortem Q&A, This Is Us creator Dan Fogelman told Deadline that “within the first couple” of episodes after the winter break, “the big mystery questions” surrounding Nicky’s story will be answered. He also indicated that Nicky would become a part of the series’ present-day storyline.

Dunne’s feature acting credits include David Michod’s satire, War Machine, opposite Brad Pitt; Dallas Buyers Club, opposite Matthew McConaughey; Martin Scorsese’s After Hours and An American Werewolf in London. In TV, he most recently starred in Jill Soloway’s I Love Dick, opposite Kevin Bacon and Kathryn Hahn, for Amazon. He will also appear in the upcoming season of Goliath.

In 2017, the documentary Dunne directed and produced, Joan Didion: The Center Will Not Hold, about his “Aunt Joan,” premiered at the New York Film Festival followed by a global release by Netflix. He is repped by UTA and Industry Entertainment.