Episode 1 : A New Hope
We find our Team still reeling from the shocking events of our climatic Season 3 ender - the loss of Agent Steve Jinx and the destruction of the Warehouse itself. Their only hope lies in racing to the other side of the Earth in a frantic race to hunt down an obscure and dangerous artifact which may or may not even exist and, even if it does exist, will using it help at all?
Episode 2 : An Evil Within
Pete and Myka investigate a mysterious case where mobs of angry people are hallucinating en masse and attacking innocents.
Episode 3 : Personal Effects
It's all hands on deck to prevent a small town from being wiped off the map when a box full of Artifacts is accidently unleashed there.
Episode 4 : There's Always a Downside
Pete and Claudia reunite with Warehouse alum Hugo (Rene Auberjonois) to track down a deadly artifact at his nephew's prep school, while Myka and Steve investigate an Artifact that is killing an up and coming musician (Sam Huntington) in New Orleans.
Episode 5 : No Pain, No Gain
Pete and Myka investigate a hockey player who seems to be miraculously and instantly recovering from serious game injuries, while Claudia is invited to a mysterious lunch by Mrs. Frederic. Elsewhere, Artie and Steve discover someone has been stealing artifacts from inside the Warehouse. Guest stars BSG actor Mike Dopud as Hockey Player "Mike Madden."
Episode 6 : Fractures
Someone has stolen Lewis Carroll?s Mirror from inside the Warehouse allowing the psychotic and murderous spirit of Alice Liddell to escape again. Our team must stop her killing spree before one of them ends up dead. Guest stars Lindsay Wagner as recurring character "Dr. Vanessa Calder."
Episode 7 : Endless Wonder
Pete and Myka cross paths with an inquisitive drug company exec when it looks like a pill is making people taller, and end up having to scramble to keep Big Pharma from discovering the Warehouse. Meanwhile Artie, Steve and Claudia track Brother Adrian to his hideout, where he has laid a deadly trap.
Episode 8 : Second Chance
Pete and Myka investigate the case of people literally rusting away in a West Virginia mill town. Steve and Claudia visit his hometown in New Jersey in a bid to end his dependence on the Metronome. Artie tells Mrs. Frederic and H.G. Wells the truth about Brother Adrian and his use of the Astrolabe.
Episode 9 : The Ones You Love
To pressure Artie into reversing the Astrolabe's effects, Brother Adrian sends deadly artifacts to Myka's pregnant sister, Pete's ex-wife and Claudia's brother. As the agents race to save their loved ones, Mrs. Frederic and Steve go to the Vatican where they discover an impossible truth about Artie and Adrian. By the end of the day, one team member lies dead in Warehouse 13.
Episode 10 : We All Fall Down
His personality split after using the Astrolabe, Artie embarks on a scheme to release a deadly virus that could wipe out half the world's population.
Episode 11 : The Living and the Dead
Following the orchid's release in Germany, Pete and Myka must race to stop a global plague before it kills half the world's population.
Episode 12 : Parks and Rehabilitation
Pete and Claudia travel to Oregon to investigate a series of earthquake-related accidents occurring in a National Park.
Episode 13 : The Big Snag
In a special, black and white noir episode, Pete and Myka are transported into an unfinished 1940s crime novel.
Episode 14 : The Sky's the Limit
Artie is blindsided when Mrs. Frederic introduces him to Abigail Chow, the new B&B manager - with ulterior motives.
Episode 15 : Instinct
HG Wells contacts Pete and Myka out of the blue to give them a tip, launching an investigation into an artifact that scares people to death.
Episode 16 : Runaway
When a volcanic event at an Arkansas State Prison allows two inmates to escape, Pete, Myka and Steve must partner with a U.S. Marshal to track down the fugitives.
Episode 17 : What Matters Most
When residents of a posh gated community start getting affected by a mysterious, versatile artifact, Myka and Pete investigate.
Episode 18 : Lost and Found
The Warehouse team uncovers a lead on a cache of artifacts stolen from Warehouse 12 by the infamous pirate, Roaring Dan Seavey.
Episode 19 : All the Time in the World
The team tracks an evil alchemist who has bronzed Claudia and stolen the only artifact that can reverse the process. The clock is ticking as Claudia?s condition apparently affects both Mrs. Frederic and the Warehouse.
Episode 20 : The Truth Hurts
The evil alchemist Paracelsus is on the run, and Pete and Myka must stop him before he achieves immortality - or something worse. Myka fights what appears to be a losing battle against cancer, while Steve learns Artie's been keeping life-altering information from Claudia.