Peggy discovers the shocking truth about Leviathan but doesn't realize that her true enemies are even closer than she imagined. Meanwhile, Souza is close to confirming the truth about Peggy and may just put her in the crosshairs of the SSR.

Peggy discovers her murder investigation has huge ramifications that can destroy her career, as well as everyone near and dear to her.

As Jarvis' precision and quick-thinking skills are put to the ultimate test, Peggy must find a way to stop an atomic explosion that threatens to destroy all of California.