The captain is assaulted by Secret Service agents, including the sinister Ghrath – whom Archer suspects is an alien. Unbeknownst to Archer at the time, Ghrath is a subordinate of Vosk, an alien of Ghrath's race and a leader in league with the Nazis. Vosk is clearly troubled by Archer's appearance. With help from insurgents named Sal and Carmine, Archer is rescued from the agents, and taken to the apartment of Alicia, an African-American woman who soon realizes that Archer may be from another time and place. She convinces her friends Sal and Carmine to help Archer, as he tries piecing together this mysterious new situation. Archer incredulously realizes that Nazis have taken over the White House and nearly the entire Eastern seaboard during a disastrous new version of World War II.

On board Enterprise, the crew faces visitors of their own. First off, time traveler Daniels appears in horrific shape, giving details that the Temporal Cold War has become an all-out conflict with dozens of agents stationed throughout the timeline to wipe out others in a fight for complete dominance. He warns T'Pol and the others that they must stop "him" ... but doesn't give any names before he collapses.

While Trip works to repair Shuttlepod One, he is assaulted by the Suliban Silik, who escapes in the vessel. Believing that the "him” Daniels mentioned must be Silik, T'Pol sends Trip and Mayweather after him, which takes them to a U.S. locale near New York where Shuttlepod One has crashed.

Meanwhile, Vosk is intent on helping the Nazis force their reach — and their concentration camps — even further. Clearly, Vosk — who says he is in total agreement with the Nazis that their race must be "pure" — is receiving assistance from the Nazis in his own way and has convinced the Germans that they are all helping each other. Still, he is mysteriously obsessed with finding Archer, whom he regards as a threat to his mission.

Vosk's command to find Archer is successful as Ghrath tracks him down. During a fateful encounter with Archer, Ghrath reveals that his race is trapped and the Germans are helping them construct a conduit so they can return home. Ghrath also confuses Archer by referring to him as a "temporal agent.” Sal, trying to save Archer from Ghrath, kills him, convinced he is a Nazi who will only bring harm. Despite Archer's disappointment in seeing his information source muted, he absconds with a communicator that Ghrath had been holding. Shortly afterward, the menacing Vosk also finds Archer. But Archer — using Ghrath's communicator to call for a transport from a stunned Enterprise — escapes from him. Archer, with Alicia in tow, is transported back aboard where a relieved crew welcomes him home.

On Enterprise, Archer meets with Daniels, who is near death. Daniels explains that Vosk leads the most dangerous faction of the Cold War who is violently opposed to the Temporal Accords. When almost captured once before, Vosk had unfortunately developed a form of stealth time travel to escape into the past. This particular World War II time juncture provides the only point where Vosk can be stopped. When Archer reveals information he learned from Ghrath — that Vosk's faction is building a conduit — Daniels urges him to destroy it. Daniels knows the conduit's destruction will be the only way to stop Vosk from destroying all other races.

And just as Archer is getting this information — and Daniels trails off to his death — Vosk kidnaps Trip and Mayweather on Earth. With them in his grasp, Vosk hopes to get — and kill — the one impediment to his grand plan: Archer.