Responding to an anonymous call from an abnormal, Magnus brings Kate and Will to an abandoned warehouse at the edge of the city. Finding it empty, and creepy to boot, they depart, but Magnus has a strange sensation and takes one last look at the place. Kate and Will, wrapped in a fog of banter, don't realize she's fallen behind. Magnus discovers the door suddenly locked, the glass unbreakable, and Will and Kate out of earshot. She begins looking for another exit, but every turn is the same, until a shadowy figure dressed in rags appears from nowhere and strikes her. Magnus tries to fight back, but the being is able to teleport, and Magnus is powerless. After toying with her, the being reveals himself as Magnus's old cohort, a mad genius named Adam who was the basis for the book "Dr. Jekyll and Mr. Hyde." The further surprise is that he knows about the hologram city, and has brought Helen here to learn what she knows.
When it becomes clear that Helen will not be able to give Adam what he wants, Adam's impulses turn from violent to murderous, and Helen, though full of questions about how Adam knows her father gave sent her the message of the city and what the keystones that Adam refers to are, must make survival a priority. She's able to evade him long enough to get enough good shots in to weaken him, but the most powerful weapon is Adam's teleportation, itself; in one of their battles, Adam's clothes ripped, exposing the skin of his arm. Now, he bears a strange wound on that spot, telling Helen that, if he's not completely covered, the teleportation will seriously injure him.
Later, as he's nursing that wound, Helen sees him dressing the tear with new cloth and coating it with some kind of oil. She has learned that Adam has altered time in this building - outside, it looks as though everything has stopped, which is why Kate and Will haven't come back to help: They're stuck in time. Devising a quick plan, Helen finds a pile of rags and fashions a headdress for herself. She dons some gloves, finds Adam's special oil, and lures the killer onto the roof. Hiding behind a chimney, she waits for the right moment and pounces on Adam, knocking him off the roof. He has no choice but to open a portal for both of them to go through, whence Helen directs them to a strategic spot and uses Adam's surprise to seriously wound him. With her enemy in this vulnerable position, Helen demands information, but Adam is a man without reason and would rather die. He shows her diodes on his wrists that begin beeping and flashing in unison with monitors all over the facility, and tells her that her father is in danger for sending her the warning in the form of the hologram.
Helen scoops the wounded sociopath in her arms and drags him toward the front door, which, having been loosed from the spell of time cast by the diodes, bursts open. The couple stagger outside, where Kate and Will stand as though no time had passed. Helen gasps out a warning, and they head back to the Sanctuary to prepare for whatever holy hell is about to find them.