Noa brings in a Waverly player with a sprained ankle, and during quarentine finds out that he's been taking his antidepressents incorrectly, leading to toxicity issue. 

An older man is brought in after vomiting and collapsing. He's had a heart transplant, but his body is rejecting the organ. The outbreak at the hospital will complicate his chances of getting a new heart. His future son in law contracts the virus. 

Angus has had to cancel on Kelly three times, and she shows up to the hospital for a coffee date in the midst of the outbreak. She stays to help until she is cleared, and then Angus forces her to leave for her own safety. 

A patient suspected of having rabies turns out to have a hemorrhagic fever. Heather is infected when the patient bites her. The CDC is brought in. Ethan does not work well with CDC rep, who is more concerned with containing the virus than treating indivual patients. and further testing shows that Elliot, Malaya, and Mario have been infected as well. The young girl, Ariel, who Leanne has taken temporary responsibility for, is also sent to the hot zone. The Deputy Director for the CDC ends up taking over control of treatment of the infected, frustrating Angel's staff left on the outside. Heather dies despite Malaya and Mario's attempts to save her. Patient zero has still not been found.