Officer Bishop tells Commander West about  Officer Ruiz’s ploy to get her to be a private informant within the department for Internal Affairs in return for clearing her for not listing her foster brother with a criminal record on her police academy forms. Ruiz will face disciplinary action while Bishop gets a formal letter of reprimand in her file. 

The rookies prepare to take their final exams later that day but they are postponed when Officers Nolan and Bishop find a dead body call in the bathroom of a bus stop and it leads to a domestic terrorist plot against the city of Los Angeles.

Two men are still at large and planning to use a weaponized strain of hemorrhagic fever. It is 90% fatal if untreated and 60% fatal if treated. There is an experimental vaccine that the CDC is flying to LA if they need it but there are limited doses.  

Nolan is upset when he realizes that Jessica knew about this threat and didn’t warn him not to let Henry come to LA. 

Officers Bradford and Chen followup up with a man who was on the bus. He took the wrong backup and the one he has is filled with “science stuff.” The man cuts his finger on one of the vials and it won’t stop bleeding. He starts coughing up blood and it lands on Bradford, who immediately shuts Chen out in the other room. 

Tim has to handcuff the man to the bed frame when he hits Tim with a chair and tries to escape. The CDC quarantines the room and Tim has to watch the man die a horrible death and contemplate if that is his future. 

Officers track down the other two men planning the attack and stop them from reaching their destination, LAX. The two men open fire on officers and take off on foot. 

Officers Lopez and West follow one onto a public bus. West puts himself in harm’s way to distract the man while Lopez shoots him. Afterward, West makes up with his father.

Nolan and Jessica track down the second suspect and have him cornered in a shed. Nolan talks the man into surrendering but Jessica shoots him, saying he was reaching for something. Nolan suspects that she lied and choose to shoot him. He begins to question whether he can trust Jessica.

Bradford gets the vaccine and his prognosis is good but the CDC plans to take him to the hospital to be monitored, but just as they are leaving the scene, Bradford passes out as his colleagues look on.