PART I: "THE SCIENCE" - As the audience enters, they are greeted by George Scherff (Ben VandenBoom), assistant to the brilliant scientist, Nikola Tesla, and the random electrical bursts of a "Tesla coil." Tesla himself (Adam Belvo) is sometimes seen peeking from behind the curtain, nervously watching as the theater is filled. Pre-show takes a surreal and sinister turn when George is suddenly approached by the strange and beautiful Creature (Jessica McVea), a being that seems particularly fixated on Tesla's eccentric assistant.

Soon, Tesla takes the stage, flanked by George and his other assistant, the lovely Dorothy Skerrit (Mary Lovely). In his opening speech, the scientist shares his many observations and philosophies, discussing humankind and its place in the universe. Tesla is later joined by The Amazing Viernik (Fred Backus), and through their overlapping monologues, we realize that the Scientist and the Magician are indeed two sides of the same coin, driven by the same passions and an intense desire to "invent."

Belgrade, Serbia, March 1908. We meet Marica, Viernik's beloved "Tavern Girl" (Carrie Johnson) mentioned in Episode 1, a beautiful young woman and the magician's object of desire when he first started performing in Belgrade. Viernik and the Tavern Girl look in wonder at brilliant flashes of lightning on the horizon, which the Tavern Girl says come from "The Tower." Tesla enters and explains the science behind Wardenclyffe Tower, a structure created to transmit wireless electricity, an invention that could provide free power to the entire world. We soon realize that the science behind Wardenclyffe is the same science behind the greatest magic trick ever performed: The Great Switcheroo.

Wardenclyffe Tower in Shoreham, Long Island, April 1910. Thanks to funding provided by J.P. Morgan (Bob Laine), Tesla is hard at work in building the second Switcheroo. We see George Scherff escorting a beautiful and more than slightly intoxicated young woman (Sam K. Taylor) into the back room of the lab, where she is instructed to stand on a metal plate. Tesla pulls a switch on the wall, and the woman is "switcherooed" with a horrible abomination, which George mercy kills with a gunshot to the head. This process is repeated two more times with two more women, and each time the poor woman is replaced with some sort of monster.

Later, Tesla's two assistants are alone, and an exhausted George reveals his feelings of guilt and rage toward these unholy experiments. Dorothy confronts George about the one abomination he let live - the beautiful Creature we saw earlier. Dorothy is heartbroken as she realizes that George is in love with this monster and flees from the room, stifling bitter tears. Soon, the Creature enters, approaching a seemingly sleeping George. She is surprised when George suddenly puts a gun under her chin - and quietly bemused when he moves the gun toward himself. Before George can take his own life, the Creature kisses him, and they clutch each other in a passionate embrace.

Meanwhile, Tesla is visited by what seems to be the ghost of George Westinghouse (Ian W. Hill), Tesla's former business partner who was murdered by Thomas Edison in Episode 6. Tesla confides in Westinghouse his confusion and frustration toward the second Switcheroo. Why isn't it working? Why these horrors and abominations? Is it because he's working alone this time, without the equations provided by Albert Einstein and the calculations provided by Edison during the creation of the first Switcheroo? Westinghouse tells Tesla that the Switcheroo is evolving, and it is the scientist's responsibility to understand and control it - or destroy it, if necessary. Tesla reveals that he thinks the Switcheroo is becoming aware and sentient, and he senses a cruelty in his creation that terrifies him.

After Westinghouse disappears, Dorothy approaches Tesla. The scientist and his assistant regard one another in grave silence, then Tesla enters the back room, standing on the metal plate. Dorothy goes to the switch and reluctantly activates the Switcheroo. Tesla cries out in pain and terror as the scientist's creation envelops him with an anger and passion we haven't seen before.

We return to the Belgrade tavern, Halloween night, 1908. Viernik enters, boasting to an angry Tavern Girl that he has captured the vukodlak, a beast found at the base of Midzor Peak (a story Viernik told in Episode 1 - and that the mysterious Varney told in Episode 7). We hear the sounds of the villagers outside, throwing rocks at the beast and preparing to string it up so it may suffer and burn in the daylight. An enraged Tavern Girl confronts Viernik about his arrogance and cruelty, putting the poor creature on display like it's one of his "stupid magic tricks." An angry Viernik reminds the Tavern Girl that it was she who told him about the vampire and demands the "thank you he deserves," violently pulling the Tavern Girl close to him. The Tavern Girl slaps him, and becomes just a memory once again as the Belgrade tavern transforms into the lab at Wardenclyffe...

Viernik, gun in hand, finds himself face to face with the Tesla-creature, the great scientist now grotesquely mutated. Viernik has traveled long and far to get to Wardenclyffe and now demands the Tesla-creature give him his greatest desire, that which has driven the magician throughout the entire series of Penny Dreadful: the Great Switcheroo. The Tesla-creature tells Viernik that the Switcheroo isn't finished - it's still changing, dying and becoming born again. Tesla tried to harness his creation and the Switcheroo punished him for trying, changing him into the Tesla-creature, a mutation that's eating him from the inside out.

The Tesla-creature tells Viernik that the Switcheroo is indeed now sentient and has evolved to become trans-dimensional, able to travel to and from worlds beyond our own, worlds that may not have existed until the Switcheroo drew from them, giving it the power of a god. And like a god, the Switcheroo is looking for a host, a body with which it can take shape and become a symbol for all to worship. And if this god has the ability to create new worlds, what's to stop it from destroying those worlds - including this one?

Tesla-creature undergoes another painful mutation, which frightens the disgusted Viernik, allowing the former scientist to go for the gun. As they struggle, Dorothy cries out, imploring them to stop. The gun goes off, and Dorothy is shot - she dies in Viernik's arms, asking for her beloved George with her final breath. Tesla-creature tells Viernik that he has a talent for hurting women: Dorothy, and Tesla's sister, Marica - Viernik's beloved Tavern Girl.

Tesla-creature, holding Viernik at gunpoint, tells the broken magician to see "what's behind the curtain." Viernik goes to the back room, standing on the familiar metal plate. After some final words from the magician, saying that there is magic in science and therefore nothing can ever be completely explained, the Tesla-creature pulls the switch and gives the Amazing Viernik his Great Switcheroo.

Viernik screams in pain as the Switcheroo envelops him. The lights in the back room explode, followed by the sound of Viernik himself exploding into a million organic pieces. Tesla-creature watches in awe as equipment malfunctions, glass breaks and Wardenclyffe is enveloped in flames. Amidst the explosions and fire, we hear the sound of heavy breathing, as if Wardenclyffe is becoming a living, breathing thing - metal is becoming flesh, machine is becoming man. The Tesla-creature can only exclaim, "Beautiful!"

Just then, George Scherff enters the lab, shooting the Tesla-creature three times. Before the Tesla-creature can fall dead, it manages to fire one shot from its own gun, which George takes right in the chest. George falls to his knees, looking at the body of his beloved Dorothy, watching as Wardenclyffe mutates and burns. The dying George can only exclaim, "Horrible!"

The Creature, trying to shield herself from the flames and explosions, enters the burning lab. She falls to her knees and holds George, attempting to shield him from the fire. George slowly takes off his gloves and puts his hands to the Creature's head, electrocuting her (we learned George's hands are electrified in Episode 8). George holds the Creature tight as she looks at him in surprise, pain, anger and sadness as the fire envelops them...

Governor's Island, the next day. Wilbur Wright's (Kevin Myers) speech to a large crowd is interrupted by the appearance of none other than Teddy Roosevelt (Bob Brader), who demands they take to the air in Wilbur's Flying Machine immediately. As they circle the Statue of Liberty, shouting over the roar of the wind and the aircraft's engine, Teddy tells Wilbur to head west to San Francisco. Wilbur tells the former President that the Flying Machine has never gone more than ten miles and lands with a bump. The crowd cheers, and Teddy is outraged that they're "back where they started." After dismissing Wilbur's Flying Machine as nothing more than a "damn Coney Island ride," Teddy pushes through the crowd: "I gotta save the world! I gotta save Caldwell!"

PART II: "THE SEANCE" - Our second story begins a few days after the burning of Wardenclyffe in the San Francisco home of Mrs. Evelyn Mowry, the mother-in-law of our intrepid detective Leslie Caldwell (Matt Gray). It is here that the detective and his wife have been hiding since acquiring the Book of Days at the end of Episode 8. Lights rise to reveal Ethel Caldwell (Dina Rose Rivera) sitting in the living room contemplating a pocket watch held in her hands. We hear the click of the front door opening and with the lightning speed we saw at the end of Episode 7, Ethel draws her gun as her mother walks in the door, giving the older woman a shock. The stern Mrs. Mowry (Robin Reed) scolds her daughter and tells her to put the gun away.

Mrs. Mowry presents to her daughter two boarding passes for a boat to Japan that leaves in four hours. To her daughter's dismay, her mother has chosen not to travel with them, unfazed by the danger that might await her if she stays. We learn that Leslie chose not to obey Joseph Pulitzer's order to destroy the Book of Days, knowing that it would be his only bargaining chip should they be captured.

When Leslie enters he is in a bit of a fluster as he prepares for one final duty before he and Ethel depart for Asia. As he starts the car and makes sure it is safe outside, Mrs. Mowry tells her daughter that Leslie is a better man "than that cowboy ever was" and that she hopes that she returns ready to start her new life. Before they depart, Leslie takes his mother-in-law aside and tells her that he has hidden the Book of Days in her basement safe and changed the combination. His final request is that if they have not returned in three hours she should burn the house to the ground.

The story continues at the home of Mr. Julius Finkle, a San Francisco medium discovered by Harry Houdini (Patrick Pizzolorusso) during his quest to uncover fraudulent spiritualists [as described in Episode 3]. The Caldwells enter to find Mr. Houdini waiting for Leslie. The great escape artist is surprised at the presence of Ethel, who Leslie explains is the one who is interested in performing a seance. Ethel asks Harry Houdini with great anticipation if it is actually true that he found a real medium.

"Of course it's true!" replies a voice in the shadows. "I'm as true as a weather cock in a summer breeze!" Into the room strides the diminutive eccentric Julius Finkle (Art Wallace). After introducing himself, Julius guides Ethel over to the seance table. Houdini excuses himself to make a phone call and Leslie and Ethel embrace before the detective exits to wait in the parlor.

Sitting at the table, the medium asks Ethel her name to which she replies, "Etta Place." She then tells Julius Finkle that the person they are looking for on the other side is none other than the famous outlaw and her former lover, Harry Longabaugh, aka The Sundance Kid. Etta places the pocket watch on the table, a gift from Sundance and a focus point as they begin the seance. After guiding her back through her memories, Finkle firmly tells Etta that the dead speak in memories and that she will appear as a memory to them. In the spirit world, a visitor cannot be heard by the dead and the living cannot understand what the dead speak. Finkle tells her to be careful to always remember that she is alive and to not get lost. Etta asks how she will know when she has arrived in the spirit world. Julius replies, "My dear, you are already there."

The room disappears around her as the lights shift to reveal the bold silhouette of a cowboy striding into view. The cowboy puts on his hat and enters the stage. The Sundance Kid (Michael Criscuolo) smiles at his former love and Etta begins to weep at seeing him again. They embrace happily and move through a series of memories - robbing a bank, lying in a field, shooting guns, visiting the St. Louis World's Fair, standing on the deck of a boat headed to South America, walking through an old Western town into the sunset...

Meanwhile, Harry Houdini and Leslie Caldwell wait in the parlor when there is a knock at the door. A little too eagerly, Houdini rises to answer it and in strides the menacing Black Max (Adam Swiderski), who immediately demands the whereabouts of the Book of Days. A fight ensues between Caldwell and the team of Black Max and Houdini, the latter of whom admits that he sold out Caldwell in the hopes of getting the Switcheroo for his own magical shows. The fight ends with Black Max shooting a powder into the face of the detective, instantly sending him into a deep sleep.

Back in the spirit world, Etta Place waits impatiently on a busy dock. Suddenly she remembers that this is only a memory and that she is waiting for Harry to arrive so that they can escape to Argentina. The lights shift as Etta is able to see into another murkier memory - silhouettes of Pinkerton detective Leslie Caldwell, gun drawn, bursting in on the Sundance Kid in bed with another woman. After a moment of hesitation, Caldwell reluctantly indicates for the Sundance Kid to make his escape. The outlaw runs out the back as police officers storm the room. But their quarry has eluded them again and this time the sheriff is none too happy with Caldwell that the Kid slipped through their fingers.

Returning to the dock, Etta realizes as Sundance arrives that this was the reason he was late that day and that Leslie must have let him escape on many other occasions as well. It dawns upon Etta that the only reason Leslie would have done that was because Leslie loved her and he knew that Etta loved Harry and would be devastated if something bad happened to the outlaw. Harry tries guiding her to the awaiting ship but Etta tries to explain to him that she doesn't love him anymore. She loves Leslie. She loves her husband.

They fail to understand each other. He doesn't really seem to hear her and he speaks in a gibberish of memories. She embraces him and says goodbye. In his arms one last time, she hears him say, "I missed you, too." To her surprise she can understand him now and he is really listening to her. It's the old Sundance she knew and loved. "It's you and me again," the cowboy smiles. "Etta Place and the Sundance Kid. Forever." But the joy turns to fear as Etta realizes that she shouldn't be able to understand anyone in the spirit world. Etta realizes something has gone terribly wrong.

The lights shift revealing the seance room of Julius Finkle as Black Max finishes slicing open Ethel's throat with a straight razor as a gagged and bound Caldwell screams in horror. Max and Houdini drag the newly widowed Caldwell from room, the dead bodies of Ethel and Julius still sitting at the table.

Elsewhere in the city at the home of Cyrus Pierce, the railroad magnate murdered by his daughter Abigail in Episode 5, President William Jennings Bryan (Merlyn Wolf Berg) is unable to get a hold of Nikola Tesla. His wife (Audrey Crabtree) enters the room holding a crowbar. The President worries that if Tesla has not sent the Switcheroo in time for the blood drinking ritual scheduled to happen at the Pierce house the following evening, the Alliance will probably kill them both. Mary Bryan tells him to worry about that later. She has found something in the basement. "Robert Ford's blood?" he wonders. "No," his wife says. "But I think I know where it went."

Deep in the wine cellar, Mary asks if William remembers why Caldwell and Viernik explored the Pierce house [in Episode 2] the year before. She explains that she noticed a place in the wall where the bricks had been removed and replaced. Putting a cross around her husband's neck and telling him to not block the sunlight, she lifts a wooden stake. "My dear, we have a vampire." From the hole in the wall, Varney (J. Malcolm Rymer) appears, hissing and baring his fangs as the lights fade to black.