Pete Lattimer is hit in the head by an artifact and wakes up to a life where he was never born. Pete must hunt down and persuade the Warehouse team (none of whom recognize him) to go on this life or death mission with him to vanquish a long dead nemesis from the past to get everyone’s lives back.

A mishap with an artifact traps Pete and Myka in a fictional 1940s world where they have to solve a murder to escape... but someone doesn't want them to. Meanwhile, Claudia and Steven convince Artie to go along with them to investigate reports of stolen cars, and Artie starts taking dangerous risks.

While the team deals with the news that Warehouse 13 is moving, Mrs. Frederic has them load their greatest memories of their missions into an artifact for future generations.