The passengers of Avias Air 514, having survived being on a plane aimed at the president, being teleported to Arizona, being killed, being resurrected, and being held in a mysterious Bio Quarantine Facility in Virginia, are now infected with a mysterious disease. And it will kill them all by morning if they don't get the antidote from Thomas, the leader of the mysterious Them. Well, the Them who aren't currently imprisoned. Thomas, you see, says he'll kill all the passengers (again!) if Sophia and the detainees aren't freed. President Martinez, not to be outdone, says that if Thomas doesn't hand over the antidote, he'll kill all the detainees himself. A compromise is finally reached, in which the passengers get the antidote and Sophia gets freed.
Meanwhile, in Texas, Sean finally gets Leila's message about being in the Snyder police office. And right after that, Leila realizes that all the cops around her are fake. Sean has a hacker buddy who tips him off at the last second before he strolls into the ambush, so he has to come up with a plan to save Leila. Naturally, he texts Vicky with a threat about her son. Classy! In the end, everyone in the police station is dead and Vicky has somehow redeemed herself by letting Sean and Leila get away. The point is that Sean and Leila are reunited, so I guess there's no reason to pay attention to them anymore.
Also, I still think the First Lady is one of Them. You just watch.
Photo credit: NBC