Halstead (Jesse Lee Soffer) may be harboring some angst against his boss, Voight (Jason Beghe), for putting Lindsay (Sophia Bush) in an uncomfortable situation in the upcoming season of "Chicago P.D."

Last installment, Voight's son, Justin (Josh Segarra), was killed. In a fit of rage, the senior detective went out to kill the culprit, but not before he told his protégé to leave so she would not witness the deed. Voight did not want Lindsay to be involved in any way in a crime he planned to commit.

It was previously revealed that the new season would see Voight in a dark place. Although he made sure to bury the dead man, the truth will eventually be revealed. There is also a huge chance that Lindsay will be implicated along with him.

TV Guide reports that Lindsay may be charged as an accessory to murder. Her boyfriend, Halstead, will be very concerned about her. As much as he knows that Lindsay considers Voight a father figure, Halstead cannot help but feel angry about the situation.

Soffer said that his character's priority would always be Lindsay's welfare. As Lindsay does her best to shield Voight, Halstead will make sure that she will not take the fall with him.

"[Voight's] a father figure to her. So she's going to try to take care of him. ... What's really important for Halstead is making sure that Lindsay doesn't end up in jail, Lindsay doesn't end up going down with Voight. ... She lost her brother, essentially. This season more than any other, Lindsay and Halstead are going to really rely on each other," the actor said in an interview with TV Guide.

Meanwhile, Lindsay's true father will probably make an appearance this season. Executive producer Matt Olmstead told Entertainment Weekly that they are planning to introduce her dad soon. Viewers already met Lindsay's mother and saw their dynamics together. This time around, details about her dad will be revealed. The EP also hinted that there would be "complications on the horizon" when the man arrives in Windy City.

"Chicago P.D." season 4 will premiere on Wednesday, Sept. 21, at 10 p.m. EDT on NBC.