As the Nazi invasion of the U.S. continues in an altered 1944, Archer and his crew map out their strategy to stop Vosk from building a time machine that will take him back to his own time and inflame the Temporal Cold War, wreaking havoc upon the timeline. Having befriended American resistance fighters intent on battling the Nazis, Archer has a ready-made force on the ground to help with his cause.
But first, he is intent on bringing Tucker and Mayweather back on board Enterprise. Vosk hails Archer, offering the chance for a rendezvous to retrieve the two men, although the alien most certainly will expect some sort of recompense. Indeed, at the meeting, Vosk clearly needs the technology aboard Enterprise to accelerate his task in building the time machine. But Archer has no intention of helping him, though Vosk insists that he is changing the timeline for the better ... despite Daniels' ardent claims otherwise. Back on board Enterprise with Tucker and Mayweather, Archer and Phlox learn that Trip isn't actually himself: the Suliban Silik has taken on his identity. Upon his exposure, Silik reveals that he has left Vosk's compound with a disk that contains schematics and other information about the time machine. Determined now to retrieve Trip — who is trapped inside the compound — and armed with the new data, Archer heads back to Earth accompanied by Silik, who shapeshifts into human form. T'Pol is left in command with orders to take out the compound as soon as Archer deactivates the shields and he gives her the go-ahead from the surface.
With the help of resistance fighters Alicia and Carmine, Archer and Silik head into Vosk's compound to deactivate the machine which is soon to be completed. Meanwhile, Alicia, Carmine and their cohorts fend off Nazi soldiers working on behalf of Vosk. However, as Archer and Silik make inroads to the machine's shields, soldiers descend on them. In the ensuing battle, Silik is wounded and dies. Just as Archer bids a farewell to him, the real Trip appears, having earlier freed himself from incarceration.
As German planes hover to protect the facility on Vosk's orders, Archer and Trip are transported back to Enterprise. Once there, Enterprise must do battle against the planes above the Manhattan skyline. Just as Vosk is about to enter a time portal, Enterprise fires upon his compound and destroys it, annihilating Vosk in the process.
Once Vosk's plan is foiled, Daniels — alive once again — appears to Archer, showing him that the timeline is resetting itself, and that all the damage Vosk caused never happened.
Within moments, finally, Archer and his crew are back to their own time, on their way home after saving Earth from the Xindi superweapon.