Tonight’s episode opened Grant sitting in a café in 1947 giving directions to Adam Barlowe about going back in time to 1939 to stop the atomic bomb from being created. Back in 2010 Allison and Carter cuddle in bed for a bit until an urgent page from Fargo took them to GD where Henry had a lead on the DED device that was stolen.
Beverly Barlowe showed Grant why they needed the DED device for the plasma cell that powered it. She told him that she can send him back to the exact moment he left. Henry and Allison investigated the area that Henry had suspicions about while Carter and Jo spoke to Zane where they realized that Grant might be involved. Further they figured out that Allison and Henry were in danger so Carter raced out to warn them but got there just as a pulse went off and threw Allison’s car into his jeep.
Carter and Henry survived the pulse but Allison did not. Carter told Henry to stay with her and went to find that where the pulse came from. He found it was a hidden workshop where Beverly and Grant had activated the new bridge device. Carter attacked Grant and both were teleported back to 1947 again but too early. When Carter explained to Grant that Allison had died, they decided to try and prevent it by stopping Adam Barlowe from stealing the bridge device plans to begin with, short of that Grant was willing to let Barlowe die when Allison saved him, or as a last resort they could warn Allison before she went back to 2010.
Everything idea that they tried failed, Adam Barlowe stole the bridge device plans, Allison was able to save his life when his heart stopped and Carter was not able to warn her before they went back to 2010, leaving Carter and Grant in 1947 again.
As Grant and Carter met back up, Grant told him that he repaired the beacon that had brought them here this time, Carter told him he was not able to warn Allison, but he then had a flash of an idea. He recorded a message to himself on the recording wire that he had listened to earlier that day.
With the new information on the recording wire, Carter made it out to Allison sooner and drove headlong into hidden building helping disperse the pulse and thus prevent Allison from being killed. Beverly Barlowe got away. Grant and Zane were cleared of all charges and Grant left to start a new life away from Eureka.