'Chicago P.D.' season 4 return date, spoilers: Sophia Bush talks Jon Seda's exit; What's next for Lindsay after learning about her father's return?

NBC's "Chicago P.D." recently wrapped up its season 4 finale with a shocking revelation, and it looks like Lindsay (Sophia Bush) will be confronting an important person in her life when the series returns next year.

Last week's fall finale ended with Lindsay responding to a text message from her mother Bunny (Markie Post), only to reveal the news that her father is back ain town and wants to meet her. As fans know, Lindsay survived 30 years of her life without the presence of her biological father, and Bunny's news left her in shock.

In a recent interview with TV Guide, Bush mentioned that the arrival of Lindsay's father creates a moment of anxiety for her. Lindsay clearly has a lot of questions in her mind, and she will struggle deciding on what to do next.

"... Why now? Does he want something?... Can Erin handle two people like that? It's a lot for her to put on her plate," the actress explained. "And so, by the time Bunny has said, 'Your dad's in town, he wants to meet you,' it's a little bit of a gut punch. And then in the next episode, we see where that goes."

 The fall finale also featured Jon Seda's departure as he heads over to the upcoming "Chicago Justice" series. Seda was first introduced on "Chicago Fire" before he moved to "Chicago P.D.," and now he will be a part of Dick Wolf's latest "Chicago" installment.

Bush said everyone on the show will miss working with Seda, but she is happy to see her co-star exploring new horizons. "Jon is just so lovely and talented and watchable and even-keeled and smart and thoughtful," she continued. "I am in no way surprised that Dick Wolf would want him to go and launch the next part of his franchise."

The fourth season of "Chicago P.D." returns to the airwaves on Wednesday, Jan. 4 at 10 p.m. ET on NBC.