An annoying floater takes a romantic interest in Violet. Ritter catches a local politician in a compromising position. Mouch and Severide help Trudy with an arson investigation.
Kate and Jack are at odds; Locke solidifies his position as leader of the Others; Juliet and Sawyer are scrutinized.
Framed for assassinating the president, Nikita is alone and on the run; Alex investigates a human trafficking ring.
Percy threatens to set off a nuclear explosion unless his demands are met; Nikita decides the best way to stop Percy is to go into Division.
Nikita talks Birkhoff into using $20 million of his own money to lure Percy into a trap; Birkhoff is arrested.