Lieutenant Henry Voight (Jason Beghe) will face some ghost in his past in episode 20 of "Chicago P.D." season 4.

The official synopsis for the upcoming episode titled "Grasping for Salvation" reveals that Voight will investigate the case of a murdered teenage boy. Things will become complicated when he finds a connection between the new case and the murder weapon that was used in a separate crime 17 years ago.

This discovery may not fare well with the victim's father (guest star Philip Casnoff), a prominent defense attorney. The summary also reveals that the father will try to have the case taken over by the Area Central Homicide Department instead.

At the moment, it is still uncertain whether the case is going to be taken away from the Intelligence Unit of the Chicago Police Department. Nonetheless, despite encountering other external pressure, Voight is still going to do his best to find out the truth about the recent murder case. However, it is not going to be easy for him, as he will be under the watchful eye of his former partner, Lieutenant Denny Woods (guest star Mykelti Williamson).

The promotional preview of the upcoming episode clip teases that Voight's past is full of demons. The recent murder case did not help, as it may also mean the end of his career.

The clip shows Voight very determined to look into the case despite all the external noise. In the preview, he says, "I'm making sure we put away the right guy."

With all the pressure of digging something from the past, ensuring that he gets the correct suspect in the recent murder case, and keeping his proper composure amid all the scrutiny around him, will Voight be able to solve the case?

Episode 20 of "Chicago P.D." season 4 airs on Wednesday, April 26, at 10 p.m. EDT on NBC.