Dr. Magnus is delivering a lecture in Rome when she is handed a note saying that she "will be killed in less than three minutes". The note was sent by Nikola Tesla, who she hasn't seen in 60 years. Tesla tells her that Cabal agents are all over the building. She hesitates, but when gunmen enter the lecture hall she follows Tesla down the stairs into a well-lit "200-year-old system of catacombs" beneath the city. The Cabal agents quickly follow. Their team leader declares that "they either surrender or they die".
Back at the Sanctuary, Will asks the Big Guy why they aren't holding the scheduled staff meeting. When told that meetings are boring, Will agrees and stops pressing the issue. The lights flicker briefly and he asks the Big Guy, who is cleaning and dusting, to investigate. "I'm not really in charge here, am I?", he asks when nothing is done. The Big Guy just chuckles. At that moment Ashley is arriving in a run-down section of town for a meeting with the Squid. But the hooded figure she greets is not the Squid. Instead, she is shot with a tranquilizer dart by John Druitt - who is supposed to be dead. Druitt then teleports away, taking Ashley with him.
Meanwhile, Dr. Magnus continues navigating the catacombs with Tesla. When two Cabal trackers catch up with them Tesla morphs into a clawed, vampire-like creature and almost kills one of them before Magnus stops him. She keeps her gun pointed at Tesla while inquiring if he has stopped taking his medication. He laughs and says no : "Come on, Helen. I don't feed on humans. I made that vow long ago, and I intend to keep it". She lowers her gun and Tesla inserts his thumb in a socket, causing more lights to come on. They continue down the corridor.
Will and the Big Guy find a large hole in the ceiling. "Scratch marks on the floor and walls, plus damage on the inside to the electrical wiring", says Will. "Whatever did this took live voltage". Henry coughs and heads off to check the surveillance cameras and security system as the Cabal crew continue their pursuit of Dr. Magnus. Tesla flashes out in front of two of them, easily knocking the pair to the ground. He is having fun while reminding 'Helen' of past times in London. Back in 1942 or '43, with every spy agency in the world searching for him, she helped Tesla fake his death and escape. He says that he believed peace would break out when she blames him for giving "every allied government" plans for his death-ray weapon. Once the Cabal soldiers move on, Magnus confronts Tesla, suspecting that they're not after her, they're after him.
Ashley awakens with a start. She is handcuffed to a chair in a large room full of mirrors. Druitt says that he needs her help. He apologizes unreservedly for his past actions and asks for her forgiveness. He tells her that her mother is in grave danger and that he needs to know where she is. Ashley, still handcuffed, has trouble believing that his concern is sincere : "You have a kind of violent way of asking for help, FYI". Druitt is surprised that her mother never revealed who he really was, only telling her that she had killed him. He impatiently insists that they have no time to waste and that she must trust him. Back in the catacombs, the pursuit continues. Dr. Magnus doesn't understand why Tesla would endanger her like this. He disappeared during World War II and he has remained hidden ever since. Nikola recollects' how they worked together at Oxford "all those years ago". He tells her that "you all changed … whereas I found out who I really am". Now the Cabal hunt him "at every turn", perceiving him as a threat. The Cabal team leader, finding his lifeless men, orders the rest to fall back and calls for the 'L-Rad' to be set up.
A beaten and bleeding Two-Face is being cared for by the Big Guy when Will arrives. He never had a chance to see his attacker : "It came from the ceiling … moved way too fast". Henry, who has been getting sicker, passes out. The Big Guy insists that he must rest and drags him away to his room. Tesla, meanwhile, reveals a seething anger when asked why the Cabal viewed him as a threat. He is part vampire and resents his kind's demise : "Humans were conquered because we were smarter and stronger. And when vampires ruled the world, it was a golden age … now people think that we're allergic to garlic and that we can turn into bats at will. It's beyond insulting". Suddenly the 'L-Rad' sends out a shock wave. Tesla pushes Helen out of the way and is impaled upon the wall. He reawakens momentarily and pulls himself away from the stake which has been driven thru his chest, joking in the voice of Dracula. Helen, ignoring that Nikola protected her, is angry at being "put in the line of fire". However she is shocked into silence when he tells her that he has always loved her - "more than that lunatic Druitt ever did".
Druitt, meanwhile, is explaining to Ashley that he knew her mother in London "when we were young". Suddenly, the disbelieving daughter breaks free of her bonds and attacks. Druitt teleports both of them to a series of dangerous locales before Ashley is forced to stop fighting. Back at the Sanctuary, Will and the Big Guy discover that the motion detectors have been disabled. They also find a reptilian-like scale and a box of Diazepam (a sedative) which has been clawed open.
As Tesla is admitting to Helen how he always admired her, Druitt continues explaining to Ashley just how close he was to her mother. He tells her that they were members of a group called 'The Five' - "dedicated to expanding our knowledge of the physical world … by the most unconventional means". Druitt explains that their longevity was not genetic but rather the result of a choice each made to 'evolve'. The other members of the group were Nigel Griffin, Sir James Watson and Nikola Tesla - the famous scientist who Druitt claims "leeched off Edison and cheated Marconi". He then inquires as to whether Ashley has ever heard of the species 'Sanguine Vampiris'. He tells her that her mother was able to procure a sample of pure ancient vampire blood, a sample which dated from before the time when vampires were killed off or sterilized. Helen Magnus derived a serum from the blood and insisted on being the first to experiment with it. In time, each of the five injected the serum and each received unique 'gifts' as a result.
Will begins to suspect that Henry is involved in the strange goings on at the Sanctuary when he sees Diazepam laying about his room and notices a cut on his leg. But the Big Guy gets angry and won't let Will question Henry. He also can't access Henry's personnel file in the computer. Strange things are happening in the catacombs as well. Tesla is almost giddy with excitement when, in the distance, the Cabal team comes under attack. He tells Helen that "the playing field just got leveled". The Cabal team leader is suddenly struck down by a vampire. "My God, Nikola, what have you done?", asks Magnus when two growling vampires appear before them. "Welcome to the future", crows Tesla.
Druitt frees Ashley and tells her that Tesla is the imminent danger her mother is facing. He challenges her to think, not just to act. There is little time, he says. At that very moment Tesla is explaining to Dr. Magnus how he created these new vampires. A little of his blood and a little of his electrical charge mixed with a dead body and, voila, instant vampire. Druitt explains how Tesla revived him after his last encounter with Helen and then tortured him when he refused to join forces. He tells Ashley that her mother will undoubtedly also refuse and that Tesla will certainly kill her. Druitt claims that the electric shock purged him of his violent rage and made him whole again. "Together", he says, "we can save her". Concurrently, Tesla is trying to convince Helen to join him. His new creations are fast, vicious and strong, but virtually mindless. He believes that she could help make them intelligent as well. "You and I could usher in a new golden age", he tells her. Tesla becomes angry when Helen looks horrified and calls him mad.
We know "abnormals are on the rise", argues Tesla, and together we can lead them. He is imagining an army of his "mini-me's" conquering the world when Magnus shoots him several times and runs away. Tesla orders his creations to get her. Earlier, back at the Sanctuary, Henry ordered Will out of his room when Will pressed him about the attacks. Now, when the elevator door opens, Will is confronted by a large reptilian creature. He flees down the hall as Magnus is fleeing down corridors of the catacombs. Suddenly, a missing-link-like creature crashes into the large reptile and drives it out the window, saving Will. As the wounded reptile slithers away, the hairy creature quickly 'evolves' back into Henry as an astonished Will watches from the broken window above.
In the catacombs, the creatures close in as Dr. Magnus runs out of ammo, only to be ordered back by Tesla. With what is presumed to be her last breath, Helen advances, bitterly insulting and taunting him. Suddenly, Druitt's fist rams through Tesla's abdomen and he teleports Helen and Ashley to safety. Helen is angry and unappreciative so Druitt teleports out, leaving Ashley to explain. Will humbly apologizes to Henry and thanks him for "saving my ass" from the big snake. Ashley now knows the truth. "He's my father, isn't he?", she asks. Yes, answers her mother, adding that she has "a lot to make up for".