When Laurel Healy returns home to Washington, D.C. to work for her brother, Senator Luke Healy, on Capitol Hill, she is caught in the midst of two huge problems: the government has stopped working due to budgetary disagreements, and mysterious bugs are eating the brains of a growing number of Congress members and Hill staffers.

When a bizarre and deadly incident takes place on live television, Agent Onofrio's investigation into it causes Laurel, Gustav and Rochelle to dig deeper into the bug mystery. Luke attempts to cover up his affair with his Chief of Staff, Scarlett, before his opponent for the minority whip position, Senator Ella Poundstone, can make it public.

Laurel asks her brother, Luke, for his help to get the Centers for Disease Control and Prevention to investigate the bugs, but he insists she first consult Dr. Joanne Alaimo, a leading entomologist, for her perspective on the invasion. Laurel’s relationship with Anthony takes a drastic turn.