Magnus (AMANDA TAPPING) returns home from an overnight trip to find the Sanctuary in a state of confounding chaos: Battle debris everywhere, no one in sight, and a scheduled UN Security Team inspection just hours away.
What started as an innocent first date for Will (ROBIN DUNNE) and Abby (PASCALE HUTTON), turns into a dangerous kidnapping by a gang whose leader faces certain death without their help.
Helen and Nikola explore an ancient Praxian stronghold, and find a little more than they were expecting. Meanwhile, Kate's past comes back to haunt her.
The Sanctuary receives reports of unexplained disappearances in Carentan in the Normandy region of France and sets off to investigate the strange occurrences.
The exodus from Hollow Earth begins, and time is of the essence as the Sanctuary stands between the abnormal refuges and the demanding UN. As they try to maintain peace, Helen receives a surprising warning from an unexpected source.
Adam Worth destroys Praxis and travels back in time to the 1890s to save his daughter. Dr. Magnus travels back in time to stop him before he damages the time line and destroys her future with it.
With Magnus gone, Will is appointed the head of the Sanctuary Network. The abnormal uprising continues to get worse. Biggie and Kate are kidnapped. As expected the surface governments respond to the uprising with deadly force.
The UN Security Council sends a task force headed by a weasel of a man, Greg Addison, to investigate the Sanctuary. His disdain for abnormals is matched by the disdain that Magnus and team have for him.
Since the UN no longer backs the Sanctuary, Magnus makes other arrangements for her finances. A planned meeting in Africa with a potential banker turns into a hostage situation. Will and Henry search for an abnormal in the Old City tunnels.
Helen and Henry break into a government abnormal research facility called SCIU - only to find it is run by Tesla. Biggie and Will deal with an annoying abnormal named Galvo.
Will's trip to Liberia turns bad when he suffers a head trauma from an attack. The trauma brings up powerful memories about his mothers death and the inadequacies of his father. Magnus deals with be-winged scam artist.
FBI Agent Abby Corrigan's life is endangered after she is suddenly attacked by an unfamiliar abnormal during an investigation; Magnus and Will's heated debate over the best way to help Abby threatens to permanently alter their relationship.
A radical group of abnormal beings plan a terrorist attack with the goal of starting a war between surface dwellers and hollow Earth inhabitants. To Magnus' disbelief, Addison, at the NSA, has proof of Biggie's leadership of the group.
When the Sanctuary is approached by an abnormal leader about a radical plan for peace, Magnus goes all in and pledges her full support. However, when Will is forced to leave the Sanctuary, his decision may just put everyone at risk.
SCIU has surrounded the 5th Ward with troops and an electric shield that prevents them from leaving. Caleb has a virus that can turn the human population into abnormals. Magnus enacts her ultimate plan for the Sanctuary network.
