The plague that's engulfed the city of Philadelphia has claimed Kate as its latest victim. With the help of the CDC's Charlie Stafford, Megan is able to stabilize her friend. Kate is quarantined as the rest of team works to determine what the ten or so people who weren't part of a cluster of victims have in common. Dani happens to be one of the outliers in question.
Since anyone who is infected dies within 72 hours, FBI Special Agent in Charge Brendan Johnson suggests that one of the victims may also be the terrorist who spread the disease. Megan visits Kate at the hospital where she learns that guy Dani met at the bar is still alive even though it's past the 72-hour mark. This man could be the terrorist. Megan has a different theory. Perhaps one of the 17 drugs he's on is keeping him alive.
Peter has been desperately trying to account for Dani's whereabouts the week before she was killed. He's also been desperately trying to get hold of her mom who is out of the country. It's been a difficult time. During an interview with a reporter, he calls the terrorist a loser and a coward. Later, Peter goes off on Megan when he feels she's being insensitive to his grief. In truth, she just can't put a stop to what's happening without him.
Megan and Charlie realize that the killer is taking meds to stay alive so that he can infect more people. They are able to identify the disease they are dealing with as virus in the Ebola class. The good news is that it's not actually Ebola. It's very rare and they should be able to determine lab from where the terrorist got it. The bad news is that there is no cure.