Chicago P.D. type TV Show network NBC

One of the many mysteries of Hailey Upton on Chicago P.D. is about to be uncovered.

Titus Welliver, the actor best known for Lost, Argo, Bosch, and so many more titles, will guest-star as Ronald Booth in the 18th episode of the season. Booth is described as “a big-time meth dealer who was recently released from prison,” according to NBC. “He can slide form chilling charm to fervent rage in an instant. He may be handsome, intense, intelligent, cunning and mercurial, but don’t let that fool you — he’s capable of anything.”

And, according to showrunner Rick Eid, one of those things is telling us a bit more about Upton (Tracy Spiridakos).

“Upton was involved with him in a prior undercover case, so she’s dusting off an old cover to try to take this guy and his crew down, and it digs up a lot of bad memories,” Eid tells EW. “She puts herself in sort of a dangerous position, and her partner and friend, Halstead (Jesse Lee Soffer), is there to try to help her.”

Chicago P.D. returns on Wednesday, Feb. 28 at 10 p.m. on NBC. The following episode marks the show’s 100th installment and is the first of a two-part crossover event with Chicago Fire. Welliver’s episode will air later this spring.

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