Wednesday's three-hour, four-part #OneChicago crossover concluded with a victory in the books for the Chicago Justice attorneys -- but one that couldn't begin to compensate for the tragic loss suffered by one member of Chicago P.D..

Despite the best efforts of Drs. Halstead (Nick Gehlfuss) and Manning (Torrey DeVitto) at Chicago Med, Alvin Olinsky's (Elias Koteas) 19-year-old daughter Lexi succumbed to injuries she sustained in a massive fire at a warehouse rave, and was one of 39 victims killed by the blaze.

Initially, the Chicago Fire crew believes the fire was accidental, but after an investigation, Severide (Taylor Kinney) discovers that it was arson -- and that whoever sent the warehouse up in flames shoved metal wedges under the doors in order to trap the victims inside. The warehouse, it turns out, was a Factory-esque location where several young artists took up residence. Though it wasn't up to code, the owner seems like he was just trying to provide a place for young people to live and work and is completely distraught by the blaze. When he's brought in by the Fire crew for questioning, he fatally shoots himself in the bathroom.

Chicago Fire is getting a new firefighter

One of the victims recovers enough to give a detailed description of the suspect, though the fire has robbed her of her sight. A young man named Dylan Oates (Peter Coventry Smith) is arrested once P.D. spots him at a vigil for the victims. Olinsky begs Voight (Jason Beghe) to let him take matters into his own hands (like Voight did with Justin earlier this season), but Voight refuses -- and luckily Antonio (Jon Seda) walks in just as things are starting to get heated between the two men.

Though none of them suffer a loss on quite the same level of Olinsky, the case takes a personal toll on several characters in the #OneChicago universe. Mouch (Christian Stolte) is also injured on the fire call when a balcony collapses on him as he's trying to rescue some of the victims Jay Halstead (Jesse Lee Soffer) fatally shoots a man who's one of the early suspects and who threatens the police; Antonio's loyalty gets questioned in his new gig at the state attorney's office when Voight falsely reports that the arson suspect confessed; and a tabloid reporter threatens to make public what sounds like an illicit weekend Stone (Philip Winchester) had with a married woman four years prior when Stone tries to get him to testify.

At the trial, a skeezy, confident defense attorney named Albert Forest (Bradley Whitford), who knows Stone's father Benjamin, is hired to represent Dylan. He tricks Stone into trying to blame Dylan's pyromania on (alleged) childhood sexual abuse, in the hopes of hanging the jury.

One Chicago: Your inside look at the four-way crossover

But Stone's one step ahead of him and eventually is able to prove that Dylan was obsessed with one of the women at the rave -- the now-blind one who identified him -- and stalked her online after she refused his advances when they met on public transportation. What's more, he's able to bait Dylan into outbursts both on the witness stand and at the defense table during Stone's closing argument, resulting in the jury finding him guilty on all counts. Moral of the story? Peter Stone is very good at his job.

The crossover was bookended by plot points rooted in actual events. The first hour, the warehouse fire, was based on the real-life 2016 fire at an artists collective in Oakland that killed 36 people. And the third hour, the official launch of Chicago Justice, touched upon the unfortunate trend of lonely, misogynistic white men committing (often mass) murder because they were rebuffed sexually by a woman.

If there's one silver lining to the whole thing, it's for Severide, who calls Anna (Charlotte Sullivan) to tell her that he misses her, only to have her show up at the firehouse to inform him that she took a job as a pediatric nurse at Chicago Med. So it looks like we'll be seeing a lot more of her in future episodes.

Chicago Fire airs Tuesdays at 8/7c on NBC; Chicago P.D. airs Wednesdays at 10/9c on NBC; Chicago Med airs Thursdays at 9/8c on NBC; Chicago Justice airs Sundays at 9/8c on NBC.