'Chicago P.D.' season 4 episode 13 spoilers: Det. Halstead goes undercover in 'I Remember Her Now'

It looks like absentee police officer Ruzek (Patrick John Flueger) is not the only one who is made for undercover work as Det. Halstead (Jesse Lee Soffer) takes on his own undercover mission in the next episode of "Chicago P.D."

The upcoming case of the week involves the crushed body of a 15-year-old girl found in an abandoned building that eventually leads Sgt. Voight's (Jason Beghe) team to a treatment center for troubled young girls. When further investigation into the case reveals that the treatment center may be involved in some corrupted dealings, Voight sends Halstead on an undercover mission to pose as a guard and work from within the center.

Halstead will soon suspect the girls of trading sexual favors for something in return and will subsequently pull the lid off the suspicious circumstances of their victim's death. What emotions will this undercover mission stir in Halstead and the rest of Voight's intelligence unit? Who will turn out to be the culprit, and what could be his or her motivation for killing a troubled 15-year-old?

Titled "I Remember Her Now," the episode will also feature Desk Sgt. Platt (Amy Morton) dealing with some feelings of guilt after realizing that the victim has been brought to District 21 in the past, but she fails to remember her now. How will Platt get over her guilt, and who will lend his or her wisdom to help the dutiful desk sergeant forgive herself and move on?

One other issue that fans of the series are hoping to be addressed soon is the matter with Det. Lindsay (Sophia Bush) and her mother, Bunny (Markie Post), after it was revealed in an earlier episode that the man Lindsay has always thought to be her father is not really her father. Bunny may have also hinted in that same episode that Voight could possibly be Lindsay's real dad, to which the Voight replied, "You wish."

Who is Lindsay's real father, and will this mystery be addressed sooner than later?

"Chicago P.D." season 4 episode 13 airs on Wednesday, Feb. 8, at 10:02 p.m. EST on NBC.