The team become involved in a number of cases of people undergo dramatic mental aberrations that see them regress to their childhood. The team searches for a cure as well as a possible connection to a high profile murder case.
Artie and Dr. Calder are reunited on a new case, but when the victims' DNAs reveal a cyber matrix, Hugo Miller, Vanessa's ex-flame, joins the investigation. The search for a cyber peeping Tom threatens to go viral unless they can find the artifact before everyone turns to clay, including Hugo, the only one who can re-write the anti-virus code. Meanwhile, Pete and Myka are retracing their steps to find out how they ended up in bed together, and what they've done to Steve who is MIA.
Claudia and Steve join a Civil War reenactment to retrieve a flask that is making the battle a bit too realistic for one of the recruits. Pete crashes his ex-wife's wedding to retrieve an ancient Egyptian mechanical bee that has the wedding party thinking the bride is their queen. And Pete explains to Myka why he kept this part of his life a secret.
Artie and Steve retrieve a Van Gogh painting, an artifact, from a New York City art gallery. Fargo, from Eureka, is trapped in a virtual role playing game he created. When the rest of the Warehouse crew joins the simulation to rescue him they find it eerily similar to their real lives.
Myka spots the elusive Leo, the man who killed her partner, which dredges up old emotions and leads Myka to uncover a bigger conspiracy. Claudia and Steve recover an artifact but are shot with tranquilizers before they can return it to the warehouse and the artifact is stolen. Which raises the question; who stole it?
With a flash and a zap, numerous people begin to disappear, leaving only a charcoal smudge behind. The Warehouse agents discover these disappearances are the result of people upsetting Megan Reese. A high school classmate and former co-worker, Jeff, has been stalking Megan and whenever she is confronted by someone, he gets rids of that person. How? Binoculars. By travelling through her memory, Pete and Jane uncover the reasons for the Regent murders: a young boy, Walter Sykes, stripped of the Collodi Bracelet. Set to destroy the Regents, how far will Sykes go to ...
Pete Lattimer (Eddie McClintock) 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 everyoneÃ.s lives back.