In the aftermath of MacPherson's invasion of Warehouse 13, the team discovers that he has abducted another prisoner from the Bronze Sector. While Artie travels to Switzerland to find Claudia, Pete and Myka go to London to find the second prisoner: H.G. Wells.

A superpowered vigilante is at large in Detroit, and the agents try to track down the person responsible. Meanwhile, things between Leena and Claudia are still tense, and Artie is haunted by the spirit of his dead friend.

A lost artifact created by Philo Farnsworth falls into the hands of an unsuspecting Univille townsperson, who inadvertently uses it to start projecting 1940s movies that take on a life of their own... and the next feature involves a mad scientist detonating a doomsday bomb. Meanwhile, Mrs. Frederic and the Regents try to determine what MacPherson left behind in Leena's mind.

Models turn up dead, aged into elderly women. To find out who is responsible, Myka goes undercover as a fashion model to find the killer... and becomes the next victim. Meanwhile, Claudia goes on a non-date with local hardware clerk Todd.

Douglas Fargo of Eureka's Global Dynamics is sent to Warehouse 13 to help update its aging computer system. This triggers a seemingly sentient computer virus that sends the Warehouse into lockdown and traps the team inside.

Mrs. Frederick secretly recruits Pete to find a mole within the organization who is buying artifacts. However, when the mole finds out, they go after those closest to Pete.

Claudia goes on her first full-fledged field mission to determine why wrestlers are spontaneously combusting. Meanwhile, H.G. Wells returns.

Pete and Myka inadvertently activate an artifact that causes them to swap bodies. However, they soon discover that the swap has fatal consequences. Meanwhile, Claudia accompanies Artie on a case involving a seduction artifact, and has to take over when Artie becomes an obsessed stalker.

Someone is using artifacts from Artie's past with the Russians to kill his allies in the present, and Helena is the prime suspect.

When ex-Warehouse agent Rebecca Sinclair brings them an unsolved case involved a newspaper editor who murdered his wife and three secretaries in 1961, Pete and Myka use H.G. Wells's time machine to travel back and try to determine what artifact was used. Meanwhile, Artie refuses to trust Helena, the newest Warehouse agent.

The deaths of three students in Egypt set off a chain of events that result in Mrs. Frederic's impending death, the appearance of a Regent, the revelation of the long-lost Warehouse 2, and the presence of a traitor within the team.

Helena's trail takes Pete and Myka from Paris to Wyoming, and they realize that she has obtained an artifact of vast destructive power... and plans to use it to destroy humanity. Meanwhile, Kelly encounters an artifact for the first time.

Pete and Myka are on the trail of a right jolly old elf who is haunting a businessman who has abandoned his family. Meanwhile, Claudia decides to give Artie the greatest Christmas gift ever and tracks down his estranged father, Isadore.