Chicago Fire Episode 3.19 I Am the Apocalypse

The squad arrives at a dangerous industrial ammonia leak and rescues dozens of victims in need of urgent care, rushing the whole lot to Chicago Med. The team's greeted by an already overloaded ER, but fearless surgeon Dr. Hannah Tramble, new addition Will Halstead (New York transplant and brother of Chicago P.D.'s Jay Halstead) and Severide's friend/nurse April Sexton vow to accommodate... that is, until a man emerges from the tumult with a grenade in his hand. He makes a strange statement about a virus being worse than Ebola and pulls the pin. Severide shoves him aside to save some lives, but the explosion that follows leaves the ER in tatters... and Severide bloody and unconscious.

To safeguard against a potential outbreak, they order a hospital lockdown - no one allowed in or out of the building. Will, April and Tramble tend to the injuries and confusion inside while Boden grapples with an angry man desperate to leave the scene of the terrorist attack. Dr. Daniel Charles, Chicago Med's chief psychologist, comes to Boden's aid and talks the man down. This allows for Boden to usher the man and a few additional stragglers back into the hospital.

Inside an operating room, Mills and Brett join Tramble in an effort to save Severide from his many wounds. They manage to stabilize him for a moment - right as Diane Claman arrives in a Hazmat suit from Infectious Disease. She starts to test the area while Casey and Otis make a scary discovery - an electrical fire rages in the ceiling and the team's out of extinguishers. This calls for supplies from outside... but the unflappable head of the hospital, Sharon Goodwin, forbids anyone - including firefighters - from entering Chicago Med and risking exposure to the possible contagion. Cruz, Mouch, Rice and the rest of the stranded team all volunteer to help and override Goodwin's decree. Their sacrifice leads to a quick and efficient beat-down of the fire, however it also means that all of the firefighters must remain inside Chicago Med.

Back outside the hospital, Halstead and Ruzek arrive from Chicago P.D. and Will informs them of the attack. They investigate as best they can without entering the scene itself and receive a major break when the parents of the attacker inform them that their son worked at a lab that studied infectious diseases. Turns out he had contact with a Soviet-era biological weapon, a specific strain of which concerns Claman. If this man passed the incubation period when he killed himself, Chicago Med may be the ground zero of an outbreak. Claman uses Herrmann's blood to sample whether or not the hospital remains infected... and he clears the test. No one is infected!

Sighs of relief ripple through the hospital as they lift the quarantine order. But a lot of uncertainty remains for Severide after a shaky series of surgeries and some makeshift coordination between Tramble, Brett and Mills. Throughout the operations, visions of Shay slip in and out of Severide's mind - could this be the end? Eventually, Tramble manages to remove all the shrapnel and Severide normalizes. He soon regains consciousness and spots April in his room. She confesses his flirtation with death scared her, and he insists he remembers nothing from the entire ordeal. April kisses him gently on the forehead... maybe that's for the best.

Later, everyone celebrates at Molly's, where Boden delivers a thankful speech for Chicago Med's incredible work today. Goodwin counters with a statement of her own and echoes his sentiment, reminding that firefighters and the hospital must always work in concert - they rely on each other's professionalism and skill. The intensity of the day seems to magnetize Dawson and Casey, and they end up in a spontaneous moment of passion. Is it just a reaction to the events in the hospital, or are they ready to reenter a relationship? They decide to ignore the big questions and just dive in - their attraction too fierce to resist.