As Cassidy waits for an ambulance with an unresponsive Burgess, Roman rushes into the apartment to search for the shooter, only to discover that none exists. Not a living one at least - the entire house is layered in trip wires and hidden compartments, more than one of which is hooked up to live ammunition. But Roman finds something even more disturbing in the bathroom: a body in an acid-filled tub.
Tests determine the body and the apartment belong to a psychology professor, yet the plates on his vehicle belong to someone else, Travis Webber. Intelligence tracks Travis to his bike shop and finds yet another heavily rigged situation. With some help from the bomb squad, the team infiltrates the shop and avoids injury, only to find Travis dead inside. And it's clearly not a suicide.
An interview with Travis' wife reveals that the two victims knew each other through Travis' dad, Isaac, another professor. A little digging leads them to a recently expelled PhD student named Spencer York whose untreated bipolar disorder led to a meltdown (and a subsequent restraining order) during his thesis defense. Intelligence heads to York's apartment - and encounters yet another series of traps. This time Ruzek unwittingly triggers a top-floor explosion.
Inside, they find Isaac unharmed, but he cannot account for his wife, Susanna. Meanwhile, Halstead and Lindsay, who's on hiatus from her new task force in order to the work the case out of loyalty to Burgess, notice York nearby, gawking at his handiwork. They arrest him and press him for information on Susanna's whereabouts, a tactic that fails due mostly to York's semi-psychotic state of mind.
Voight interviews Isaac again, insistent that even embarrassing details could help find Susanna. This causes Isaac to admit to Susanna's infidelity with a client and leads Intelligence to her location - only this time there's only one trap. A terrified Susanna cries, a bomb taped to her chest and a perimeter of trip wires rigged all around her. Except, the trip wires are fake and Halstead discovers Susanna's bomb is on a timer, with less than two minutes before detonation. The seconds tick down as Halstead fields instructions from the bomb squad outside... and barely manages to defuse the bomb in time.
At Chicago Med, Burgess lays unconscious for hours and endures a series of surgeries - and visitors (even Sergeant Platt). When she finally comes to, Ruzek embraces her and they express their love for each other. Voight stops by later and brings more than just well wishes: he offers her Lindsay's spot on Intelligence, despite his knowledge of her and Ruzek's relationship.
After her release from the hospital, however, Burgess awakes in the middle of the night and looks at herself - and her wounds - in the mirror. Is she ready to work Intelligence?