As SCIU threatens the nascent Abnormal "Homeland" (with a deadly weapon partly designed by Nikola Tesla), both Magnus and Caleb come under "friendly" fire. Cornered and determined, Magnus responds with a daring move no one - on either side - sees coming.
Magnus is asked to help broker a peace agreement between Caleb, a Hollow Earth insurgent leader, and the world's governments - an agreement whereby Abnormals would be permitted to settle on the surface. Preparing to take military action against the Abnormal forces, Addison "drafts" Will back into the federal government, further dividing Team Sanctuary.moreless
Seeking to outrace the SCIU (who are attempting to capture a rare, legendary Abnormal), Magnus and Will are captured, injured and trapped in a Bolivian cave-in. Alone, the two friends struggle to survive - as they confront who they are and who they've become.
Kate returns from Hollow Earth with word that insurgents are about to strike an above-ground target - and may have inside help from a trusted member of Team Sanctuary.
Just when Magnus thought Adam Worth was gone forever, she and Tesla become trapped in a virtual Sanctuary, where they are attacked by an avatar of Worth - who is determined to enter the "real" world.
When a previously unknown Abnormal attacks Abby, Magnus and Will attempt to communicate with the creature using music - while Henry and Gavin retrace Abby's steps to find out what happened.
Team Sanctuary investigates a mystery on the high seas when the shipwrecked crew of a Bering Sea icebreaker murders the Abnormals on board and then turns on each other.
While Magnus deals with two ne'er-do-well flying Abnormals who entangle her in a wild scheme, Will takes a road trip to Monrovia - where he is unsettled by personal revelations and temporarily blinded during a riot.
Magnus and Henry attempt to infiltrate a secret Abnormal testing facility run by Homeland Security and encounter an old friend whose loyalties are once again in question - Nikola Tesla.
Intending to meet with her mysterious new financial adviser, Magnus flies off to a remote African island - only to become embroiled in a dangerous hostage situation. Meanwhile, back at the fort, Will and Henry have their hands full tracking an escaped Steno.
Team Sanctuary comes under fire from a U.N. inspector who threatens to cut off their funding and shut them down - attempting to turn Will against Magnus in the process. Meanwhile, Erika visits Henry, warning him of a potentially dangerous new dilemma.
As Abnormals continue to pour out of Hollow Earth, Team Sanctuary seeks to prevent the Lotus Security Forces from committing "xenocide" - while searching for and worrying about Magnus, who was last seen heading towards Praxis just before it was obliterated.
In order to prevent him from altering - or destroying - the future, Magnus uses Adam Worth's time portal to pursue him to 1898 London.