'This Is Us': Sophia Bush Joins Season 4 in Mysterious Role
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Is Kevin Pearson about to meet his forever love?

This Is Us has cast Sophia Bush in a mysterious role for the fourth season, ET has confirmed. Bush, whose last major TV role was as a cop on Chicago PD, will guest star in the current season.

According toDeadline, Bush's storyline will be centered almost exclusively around Kevin (Justin Hartley), who declared at the end of the fall finale his desire to get married and have a family. In a flash-forward, it is revealed that Kevin is happily in a relationship and expecting a baby. 

“The story of who is the mother of Kevin’s child and all that journey will be a story in the back half of the season, and there will be an answer by the end of the season,” creator Dan Fogelman told reporters over the weekend at the winter Television Critics Association press tour. Fogelman did not confirm whether Bush's character is the mother of Kevin's child.

Better Things star Pamela Adlon will also drop by This Is Us this season. Her storyline will revolve around Randall (Sterling K. Brown).

Brown shared during the panel that Randall's upcoming storyline is "quite compelling and allows us to deliver further into Randall's mental health and how he takes care of himself, what's right and what's wrong about how he takes care of himself and how he could possibly do a better job at that."

The actor added that the Randall-centric episode has a dramatic turn that prompted a visceral reaction: "Then this moment happens where you're like, 'Oh s**t, this is about to go a little sideways.'"

“She has an unbelievable arc in the back of the season, she plays a limited but very important part of that story," Fogelman told Deadline.

Bush and Adlon are just the newest additions to This Is Us, which will welcome John Legend in Tuesday's winter return. 

This Is Us returns Tuesday, Jan. 14 at 9 p.m. ET/PT on NBC.

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